Power attack damage

[Jingwei]

Here's my attempt to show power attack damage:

As our sample character:
LVL 20 WF favored soul, full WF power attack enhancement (-8 to hit), IC: slash, +2 great sword damage enhancement.
To hit:

15 bab
15 40 str
1 fvs greatsword
5 divine power
3 divine favor
4 greater heroism
1 haste
5 weapon
3 ship buffs
=
52

Using a Lit2 greatsword, and wearing a +6 seeker item.
Assumption: seeker effects still work like on live, by modifying the d20 confirmation roll.


here's the damage numbers I'm working with:
(Ignoring the on vorpal shocking blast damage bonus)

                normal    critical
base damage       10.5       21
str               22         44
fvs favored wpn    4          8
divine favor       3          6
weapon +           5         10
power attack     (16)       (32)
        
holy               7          7
shocking           3.5        3.5
lightning strike   9.15       9.15
      
shocking burst                5.5
shocking blast                5.5

seeker                       12
       
final damage      64.15     131.65
                 (80.15)   (163.65)

Expected Damage:

AC    base    normal  critical dmg/swing
      hit     hit     hit
            normal attack
40    0.95    0.75    0.2      74.4425
45    0.95    0.75    0.2      74.4425
50    0.9     0.7     0.2      71.235
55    0.8     0.6     0.2      64.82
60    0.75    0.55    0.2      61.6125
65    0.75    0.55    0.2      61.6125
70    0.7     0.5     0.2      58.405
75    0.65    0.46    0.19     54.5225

            power attack
40    0.95    0.75    0.2      92.8425
45    0.85    0.65    0.2      84.8275
50    0.8     0.6     0.2      80.82
55    0.75    0.55    0.2      76.8125
60    0.7     0.5     0.2      72.805
65    0.65    0.46    0.19     67.9625
70    0.65    0.46    0.19     67.9625
75    0.6     0.42    0.18     63.12

----------------------

For lulz, we'll try the same setup with an (regular) SoS

AC  normal  power attack
40   58.95   80.55
45   58.95   74.85
50   56.9    72
55   52.8    69.15
60   50.75   66.3
65   50.75   62.13
70   48.7    62.13
75   45.65   57.96

and the eSoS

AC   normal   power
40   79.875   101.475
45   79.875   97.85
50   79.875   94.225
55   74.225   90.6
60   71.4     86.975
65   68.575   83.35
70   68.575   83.35
75   65.75    78.095

----------------

how about a FVS that doesn't try so hard?
to hit:

15 bab
10 30 str
1 fvs greatsword
3 divine favor
5 weapon
=
34

(but he still has a lit2 greatsword and +6 seeker)

AC   base  norm  crit  dmg per
     hit   hit   hit   swing
normal attack
40   0.8   0.6   0.2   69.82
45   0.75  0.55  0.2   66.3625
50   0.7   0.5   0.2   62.905
55   0.65  0.46  0.19  58.7225
60   0.6   0.42  0.18  54.54
65   0.6   0.42  0.18  54.54
70   0.55  0.38  0.17  50.3575
75   0.55  0.38  0.17  50.3575

power attack            
40   0.7   0.5   0.2   77.305
45   0.65  0.46  0.19  72.1625
50   0.6   0.42  0.18  67.02
55   0.6   0.42  0.18  67.02
60   0.55  0.38  0.17  61.8775
65   0.55  0.38  0.17  61.8775
70   0.5   0.34  0.16  56.735
75   0.5   0.34  0.16  56.735

------------------

1. anyone see any holes in my numbers or computations?

2. anyone see any problems with computing based on those AC ranges?

3. Anyone want to see numbers for different builds?

But the conclusion looks like:
If your class or race offers more power attack damage, take it.
Turn power attack on when logging in.
Remember to turn it back on if you got logged out.

[Jingwei]

Here's some more data:

This table shows the advantage (in damage per swing) you get from having WF power attack on, keeping the base damage the same (str 40 WF FVS, lit2 GS, seeker 6)

AC                  Attack bonus
    56     54     52     50     48     46     44     42    40     38
40  18.4   18.4   18.4   14.39  14.39  10.39  10.39  9.59   9.59  8.79
45  14.39  14.39  10.39  13.59   9.59   9.59   8.79  8.79   7.99  7.99
50  13.59   9.59   9.59  12.79   8.79  11.99   7.99  7.99  11.19  6.35
55  12.79   8.79  11.99  11.99   7.99  11.19   6.35  6.35   9.56  4.72
60  11.99   7.99  11.19  11.19   6.35   9.56   9.56  4.72   8.6   8.6
65  11.19  11.19   6.35   9.56   9.56   4.72   8.6   8.6    8.6   7.64
70   6.35   9.56   9.56   9.56   8.6    8.6    8.6   3.76   7.64  7.64
75   9.56   9.56   8.6    8.6    8.6    3.76   7.64  7.64   7.64  6.68

So, where there are negative numbers, it's better if you have power attack turned off.

There aren't any, so don't turn power attack off.

---------------

Next, the advantage from taking the 3 points of WF power attack, how much of a damage advantage do you get?
This compares running basic power attack to the full WF power attack, where a negative number, indicates that WF power attack is worse, and a positive number shows it being better.

AC           Base to hit
    56    54    52    50    48    46    44    42    40    38
40  6.9   6.9   6.9   2.89  6.6   2.59  6.3   2.29  6     1.99
45  2.89  6.6   2.59  6.3   2.29  6     1.99  1.99  1.69  1.69
50  6.3   2.29  2.29  6     1.99  5.7   1.69  1.69  5.4   0.56
55  6     1.99  5.7   5.7   1.69  5.4   0.56  0.56  5.04  0.2
60  5.7   1.69  1.69  5.4   0.56  0.56  5.04  0.2   0.2   4.68
65  5.4   5.4   0.56  0.56  5.04  0.2   0.2   4.68  4.68 -0.16
70  0.56  0.56  5.04  5.04  0.2   4.68  4.68 -0.16 -0.16  4.32
75  5.04  5.04  0.2   4.68  4.68 -0.16 -0.16  4.32  4.32 -0.52

So, it never really hurts to have WF power attack turned on. You'll have to plug your own character numbers into ye [s]olde[/s] new arcane formulae and see if you think it's worth the AP.

[Jingwei]

[edit] done, new table up, showing precision is a trap with slightly different numbers.


Here's a comparison of precision (+5% to hit, right?) vs 'regular' (as opposed to WF) power attack.

Positive numbers show where power attack is better
(measuring in damage per swing, not accounting for increased AB from later swings, etc).

AC         Base to hit
    56    54     52    50    48    46    44    42    40    38
40  11.5  11.5  11.5  11.5   7.79  7.79  4.09  4.09  0.38  3.58
45  11.5   7.79  7.79  4.09  4.09  0.38  3.58  3.58  3.08  3.08
50   4.09  4.09  4.09  3.58  3.58  3.08  3.08  3.08  2.58  2.58
55   3.58  3.58  3.08  3.08  3.08  2.58  2.58  2.58  1.31  1.31
60   3.08  3.08  6.29  2.58  2.58  5.79  1.31  1.31  4.52  0.04
65   2.58  2.58  2.58  5.79  1.31  1.31  4.52  0.04  0.04  3.92
70   2.58  5.79  1.31  1.31  4.52  0.04  0.04  0.04  3.92 -0.57
75   1.31  1.31  4.52  0.04  0.04  0.04  3.92 -0.57 -0.57  3.32

Remember that I'm using a particular setup, so the advantages of precision vs power attack may change depending on gear and build. Have them in a spreadsheet, you can ask for number on a particular setup if you want.

[Jingwei]

Sigh, post got eaten by the login monster.

Was posting for 1H weapon fighters (Str 40, lit2 kopesh, seeker 6)

Short version:
Power attack still something you turn on all the time.
WF power attack still something that pretty much always increases damage.

Precision still generally worse than power attack.

[Jingwei]

And what about the caster who wants to be 'a helper' when he's out of SP and brings out his lit2 staff and starts swinging? Should he take power attack too? Didn't look at as many numbers, but yes, even he does more damage with power attack turned on. He also does more average damage, hahahaha, if he takes the full WF power attack enhancement.

How about precision? Nope, power attack still providing more damage than precision.

[krogyy]

have you counted also the confirmation roll for the criticals?

Edit: scratch that, i see you did.

[Stillwaters]

+1

Ty for the well constructed info,
I assumed PA was better for THF, Never expected to see it was better 99% of the time regardless of to hit though

I might link this from the Whirlwind vs Cleaves thread as it shows yet another reason whirlwind is a trap.

[zealous]

Here's my attempt to show power attack damage:
1. anyone see any holes in my numbers or computations?

2. anyone see any problems with computing based on those AC ranges?

3. Anyone want to see numbers for different builds?

1. Something seems amiss with your calculations, more specifically the critical hit column seems somewhat too high.
e.g. example 1 with 52 tohit +12 seeker +10.5 pseudo roll =+74.5 toconfirm vs. 60AC
74.5/(2*60)+0.25~0.85; 0.85*0.2=0.17!=0.2

3. For a low twink FVS, PA will contribute a relatively large percentage of base damage, and damage as a whole. Weapons with higher crit profiles will suffer less against higher AC given that you have seeker effects, relatively large percentage of damage is from crits, crits miss less than regular attacks. As such, this is close to the best case scenario for PA.

Worse case scenarios would include lower crit profile weapons, many damage effects as well as base damage increasing buffs and equipment. So let's say a wraps using rogue with maxed SA as well as all base damage increasing equipment and buffs?
Or a geared and buffed barb?
[edit]With a low crit profile and many +d6 effects, seeker will be less beneficial and PA(and base damage) contribute a relatively smaller percentage of damage as a whole

[Jingwei]

MY assumption was that seeker added a flat percentage to the critical confirmation, i.e. seeker +6 was +30% to confirm critical hits. Don't know if this is actually the case.

Here's the sample data on a rogue 20.

15 bab
15 40 str
4 greater heroism
1 haste
5 weapon
3 ship
4 sneak attack accuracy IV
4 sneak attack item +4
-4 twf
=
47

(lit2 rapier, seeker +6, sneak +4 item)
Damage:

               normal  critical
base damage     5.25     10.5
str            15        30
weapon +        5        10
power attack   (5)      (10)
    
holy            7         7
shocking        3.5       3.5
lightning       9.15      9.15
    
sneak          35        35
sneak training 12        12
sneak item      6         6
                  
critical               
shocking burst            5.5
shocking blast            5.5
                      
seeker                   12
                       
               97.9     146.15
             (102.9)   (156.15)

Power attack advantage:

AC           to hit
    55    53    51    49    47    45    43    41    39
30  6.25  6.25  6.25  6.25  6.25  6.25  6.25  6.25  6.25
35  6.25  6.25  6.25  6.25  6.25  6.25  6.25  1.11  1.11
40  6.25  6.25  6.25  6.25  1.11  1.11  0.85  0.85  0.61
45  1.11  1.11  1.11  0.85  0.85  0.61  0.61  0.36  0.36
50  0.85  0.85  0.61  0.61  0.61  0.36  0.36  0.1   0.1
55  0.61  0.61  0.36  0.36  5.25  0.1   0.1  -0.94 -0.94
60  0.36  0.36  0.1   0.1   0.1  -0.94 -0.94 -0.94 -1.27
65  0.1   0.1   5    -0.94 -0.94 -0.94 -1.27 -1.27 -1.27
70  5    -0.94 -0.94 -0.94  4.68 -1.27 -1.27  4.35 -1.59
75 -0.94  4.68  4.68 -1.27 -1.27  4.35 -1.59 -1.59 -1.59

precision vs power attack
(negative numbers show precision advantage)

AC          to hit
    55    53    51    49    47    45    43    41    39
30  6.25  6.25  6.25  6.25  6.25  6.25  6.25  6.25  6.25
35  6.25  6.25  6.25  6.25  6.25  6.25  6.25  1.11  1.11
40  6.25  6.25  6.25  6.25  1.11  1.11 -4.04 -4.04 -4.29
45  1.11  1.11  1.11 -4.04 -4.04 -4.29 -4.29 -4.54 -4.54
50 -4.04 -4.04 -4.29 -4.29 -4.29 -4.54 -4.54 -4.79 -4.79
55 -4.29 -4.29 -4.54 -4.54  0.36 -4.79 -4.79 -5.84 -5.84
60 -4.54 -4.54 -4.79 -4.79 -4.79 -5.84 -5.84 -5.84 -6.89
65 -4.79 -4.79  0.1  -5.84 -5.84 -5.84 -6.89 -6.89 -6.89
70  0.1  -5.84 -5.84 -5.84 -0.94 -6.89 -6.89 -1.27 -7.21
75 -5.84 -0.94 -0.94 -6.89 -6.89 -1.27 -7.21 -7.21 -7.21

[edit] original precision v power attack table had seeker turned off.

[edit 2]
Will try to work up some data vs fortified targets later, will be more complex because I'll have to modify sneak attack damage too...

[Jingwei]

Barbarian

20 bab
25 60 str
4 greater heroism
1 haste
5 weapon
3 ship
=
58

damage: (10% crit threat, x6 crit multiple)

              normal  critical
base damage     9.75    58.5
str            37      222
weapon          5       30
power attack  (16)     (96)
    
holy            7        7
shocking        3.5      3.5
lightning       9.15     9.15
    
frenzy         18       18
critical                  
shocking burst          11 
shocking blast          11
                         
seeker                  36
               89.4    406.15
             (105.4)  (502.15)

Does the extra damage from burst effects get increased by the barbarians increased critical multiplier?

barbarian power attack (-8) advantage over regular attack

AC          to Hit
    66     64     62     60     58     56     54     52     50
30  23.2   23.2   23.2   23.2   23.2   23.2   23.2   23.2   23.2
35  23.2   23.2   23.2   23.2   23.2   23.2   23.2   23.2   23.2
40  23.2   23.2   23.2   23.2   23.2   23.2   23.2   23.2   17.93
45  23.2   23.2   23.2   23.2   17.93  17.93  17.93  12.66  17.13
50  23.2   17.93  17.93  17.93  12.66  17.13  11.86  11.86  16.33
55  12.66  12.66  17.13  11.86  16.33  16.33  11.06  15.53  15.53
60  11.86  16.33  16.33  11.06  15.53  15.53  10.26  14.73  14.73
65  16.33  15.53  15.53  15.53  10.26  14.73  14.73   7.48  11.95
70  15.53  15.53  14.73  14.73  14.73   7.48  11.95  11.95  11.95
75  14.73  14.73  14.73  11.95  11.95  11.95  11.95  10.75  10.75

precision is never even in the running

and comparing regular power attack to barbarian power attack, there's a disadvantage spot, roughly around AC 60-65, where regular power attack is better, but I don't feel like reformatting more tables right now.

[wax_on_wax_off]

Looking at the rogue one is reassuring but could you do something specific for a handwraps rogue build like the Black Lotus (19 rogue/1 monk) or the build in my sig (18 rogue/2 monk)? I asssume that power attack loses more ground but not sure.

Would the conclusions change if seeker doesn't add +30% confirmation but instead works differently?

Would the conclusions change if rounding didn't occur (and rounding was just a visual thing)?

[Jingwei]

[edit]
ok, tables should now be fixed, slightly different precision vs power attack conclusion.

OK, not sure I have all the build details worked out, but here's the numbers I'm using:

To hit:

15 bab
15 str 40 (after ship buff?)
4 sneak attack traning IV
4 sneak attack item
7 slotted air/air/air handwraps
4 GH
1 haste
3 ship (think litany and kobold bonus don't stack?)
=

53

Damage:
1d6 base hand wrap damage
+7 enhancement
+4 sneak attack training
+6 sneak attack item
+12d6 sneak attack (9 from rogue 18, 3 from assassin III)
shocking burst on wraps
lightning strike on wraps
acid burst ring
holy burst ring

don't want to compute:
eletrical storm vorpal effect
will assume acid burst ring instead of stalker ring, until someone comes up with how seeker works.

damage numbers:

              normal  critical
base damage     3.5      7
str            15       30
weapon +        7       14
power attack   (5)     (10)
ship            2        4
                             
acid            3.5      3.5
holy            7        7
shocking        3.5      3.5
lightning       9.15     9.15
                            
sneak          52       52
                                 
critical    
shocking burst           5.5
holy burst              10.5
acid burst               5.5
                             
              102.65   151.65
             (107.65) (161.65)

power attack advantage:

AC             to hit
     61   59    57    55    53    51    49    47    45    43
30  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25
35  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  4.98  4.98
40  5.25  5.25  5.25  5.25  5.25  4.98  4.98 -0.43 -0.43 -0.7
45  5.25  4.98  4.98 -0.67 -0.43 -0.43 -0.7  -0.7  -0.98 -0.98
50 -0.43 -0.43 -0.43 -0.7  -0.7  -0.98 -0.98 -0.98 -1.25 -1.25
55 -0.7  -0.7  -0.98 -0.98 -0.98 -1.25 -1.25  4.13 -1.53 -1.53
60 -0.98 -0.98 -1.25 -1.25 -1.25 -1.53 -1.53 -1.53 -1.8  -1.8
65 -1.25 -1.25  4.13 -1.53 -1.53  3.85 -1.8  -1.8  -1.8  -2.08
70  4.13 -1.53 -1.53  3.85 -1.8  -1.8  -1.8   3.58 -2.08 -2.08
75 -1.53  3.85 -1.8  -1.8   3.58  3.58 -2.08 -2.08  3.3  -2.35

precision vs power attack, positive numbers show power attack advantage

AC         to hit
    61    59    57    55    53    51    49    47    45    43
30  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25
35  5.25  5.25  5.25  5.25  5.25  5.25  5.25  5.25  4.98  4.98
40  5.25  5.25  5.25  5.25  5.25  4.98  4.98 -0.67 -0.67 -6.08
45  5.25  4.98  4.98 -0.67 -0.67 -0.67 -6.08 -6.08 -6.36 -6.36
50 -0.67 -0.67 -0.67 -6.08 -6.08 -6.36 -6.36 -6.36 -6.63 -6.63
55 -6.08 -6.08 -6.36 -6.36 -6.36 -6.63 -6.63 -1.25 -6.91 -6.91
60 -6.36 -6.36 -6.63 -6.63 -6.63 -6.91 -6.91 -6.91 -7.18 -7.18
65 -6.63 -6.63 -1.25 -6.91 -6.91 -1.53 -7.18 -7.18 -7.18 -7.46
70 -1.25 -6.91 -6.91 -1.53 -7.18 -7.18 -7.18 -1.8  -7.46 -7.46
75 -6.91 -1.53 -7.18 -7.18 -1.8  -1.8  -7.46 -7.46 -2.08 -7.73

Some non exhaustive estimates of 75% fortification say that the advantage of precision keeps roughly the same break points (around ac 45 to 50), but the advantage shrinks to on the order of 2 to 3 points of damage a swing at higher ACs. Power attack marginally advantageous vs normal attack at 75% target fortification.

[Jingwei]

Can anyone confirm that sneak attack damage is applying to the grazing hits? That would change rogue numbers considerably.

If that is the case, with the rogue18/monk 2 build above, power attack is always better than normal attack. Precision gets about a points of damage advantage over power attack around AC 60, and has roughly the same ~1 point of damage advantage over AC 60 at 75% target fortification.

[MRMechMan]

[edit]

power attack advantage:

AC             to hit
     61   59    57    55    53    51    49    47    45    43
55 -0.7  -0.7  -0.98 -0.98 -0.98 -1.25 -1.25  4.13 -1.53 -1.53

65 -1.25 -1.25  4.13 -1.53 -1.53  3.85 -1.8  -1.8  -1.8  -2.08
70  4.13 -1.53 -1.53  3.85 -1.8  -1.8  -1.8   3.58 -2.08 -2.08
75 -1.53  3.85 -1.8  -1.8   3.58  3.58 -2.08 -2.08  3.3  -2.35

Any reasons for the flip-flopping? I imagined the curve would be smoother.

From what I can surmise, PA is quite a bit better than it was for MOST players. The Barbs that were hitting everything 95% of the time will see more misses due to the new system, but rogues/monks etc that were not totally geared and PA meant 25% more misses...well it now only means 5% more misses and generally is worth it.

Not sure how I feel about it still.

Basically the more geared/PLed/built you are, the more this AC change hurts you. If your to-hit was abysmal, it is likely a buff. To-hit gear/fighter PLs are now quite a bit more useless than before-it just doesn't matter.

[Jingwei]

Any reasons for the flip-flopping? I imagined the curve would be smoother.

largely becuase of the 5% rounding, but also beause the actual to hit penalty of power attack goes down as AC goes up.

Here's data from the comparison of barbarian power attack vs normal attack:

rounded

AC  regular  power  difference
30  0.95     0.95   0.00
35  0.95     0.95   0.00
40  0.95     0.95   0.00
45  0.95     0.90   0.05
50  0.90     0.80   0.10
55  0.85     0.75   0.10
60  0.80     0.70   0.10
65  0.75     0.70   0.05
70  0.70     0.65   0.05
75  0.70     0.65   0.05

unrounded

AC  regular  power  difference
30  0.95     0.95   0.00
35  0.95     0.95   0.00
40  0.95     0.95   0.00
45  0.95     0.88   0.07
50  0.90     0.82   0.08
55  0.84     0.76   0.08
60  0.79     0.72   0.07
65  0.75     0.68   0.07
70  0.71     0.65   0.06
75  0.68     0.63   0.05

[MRMechMan]

largely becuase of the 5% rounding, but also beause the actual to hit penalty of power attack goes down as AC goes up.

Here's data from the comparison of barbarian power attack vs normal attack:

rounded

AC  regular  power  difference
30  0.95     0.95   0.00
35  0.95     0.95   0.00
40  0.95     0.95   0.00
45  0.95     0.90   0.05
50  0.90     0.80   0.10
55  0.85     0.75   0.10
60  0.80     0.70   0.10
65  0.75     0.70   0.05
70  0.70     0.65   0.05
75  0.70     0.65   0.05

unrounded

AC  regular  power  difference
30  0.95     0.95   0.00
35  0.95     0.95   0.00
40  0.95     0.95   0.00
45  0.95     0.88   0.07
50  0.90     0.82   0.08
55  0.84     0.76   0.08
60  0.79     0.72   0.07
65  0.75     0.68   0.07
70  0.71     0.65   0.06
75  0.68     0.63   0.05

Thanks, makes more sense.

Zomg just got my ravens sight shard! w00t +4 to-hit! *Crafts quickly*. /no difference?

Ohh yea just got 3p abishai set! 3 more AC! Can't touch this na na n- /no difference?

This trying to cram a d100 into a d20 is just trouble.

[zealous]

MY assumption was that seeker added a flat percentage to the critical confirmation, i.e. seeker +6 was +30% to confirm critical hits. Don't know if this is actually the case.

afaik seeker has always been a bonus to the confirm roll, not a static percentage bonus. I have not seen any mention of it being changed to a flat percentage but there might be some dev post I have missed? Or player testing?

Can anyone confirm that sneak attack damage is applying to the grazing hits? That would change rogue numbers considerably.

Grazing hit's should be only weapon damage afaik.

[Jingwei]

afaik seeker has always been a bonus to the confirm roll, not a static percentage bonus. I have not seen any mention of it being changed to a flat percentage but there might be some dev post I have missed? Or player testing?.

In the old system, if you had a .60 (hit on a 9)chance to hit, and are wearing seeker +6, you'd confirm critical hits on a .90 (confirm on a 3). So a +30% to confirm critical hits. The other option is that you re-roll your to hit, using the new numbers, but add +6 to your basic to hit chance. This would make seeker +6 provide on the order of a 5% increase in your chance to confirm critical hits.

[Khellendros13]

Am I the only one that finds is preposterous that 53 to hit is more DPS than 55 to hit, with PA turned on?

That really makes no logical sense...so now I need to change my to hit depending on the ac of who I am fighting, depending also one what is factoring into my overall damage?

Can a dev explain why this is the case? Why can't more to hit simply mean you hit more often, and once you pass the maximum chance to hit, it just makes no difference rather than losing you DPS?

[Jingwei]

Am I the only one that finds is preposterous that 53 to hit is more DPS than 55 to hit, with PA turned on?

That really makes no logical sense...so now I need to change my to hit depending on the ac of who I am fighting, depending also one what is factoring into my overall damage?

Can a dev explain why this is the case? Why can't more to hit simply mean you hit more often, and once you pass the maximum chance to hit, it just makes no difference rather than losing you DPS?

Sounds like you are reading the tables wrong. I never make any statements about how much damage you do, just whether you do more or less damage with power attack turned on.

So, for example, looking at the rogue numbers, if your base to hit is 55, and you are fighting a 0 fort monster with AC 70, your 1st swing will do more damage with power attack on. But if you are fighting a monster with 65 or 75 AC, you'll do less damage with power attack on.

Since these rounding spikes occur in relatively random places, you won't be able to compute them during the quest, and your to hit will change a lot anyway, as buff get cast or wear off, you get flanking, etc. So, the thing to do is to put your build into the spreadsheets, see if power attack is generally advantageous or not, and if there is a cut-off where it stops becoming advantageous. If there is one, turn power attack off.

So, using the rouge/monk example again, you'd want to turn power attack off around 45 if you were generally well buffed, or off around AC 40 if you were missing buffs while the FVS and barbarian don't want to turn off power attack, at least up to AC 75.