Here's what I got when I did some mathsmithing on a falchion over 20 swings (crit 14-20/x2):
POS/ear/ear falchion vs EVIL
2d6+1d6+1d10c
199.5+38.5
238
ear/POS/ear falchion vs EVIL & NEUTRAL
1d6+1d6+3d6c
133+73.5
206.5
POS/ear/ear falchion vs NEUTRAL
1d6+1d10c
66.5+38.5
105
pos/ear/ear is...
+1.5/swing vs evil
-5.0/swing vs neutral
So you're getting a bit more per swing against evil creatures by going holy and losing three times that differece against neutral. Judge for yourself if its worth it. For me, im torn on the issue because I will be using my weapon against everything as a kensei III, and not just a boss-beater. Keep in mind that the holy weapon is doing more acid damage than the good burst weapon as well, which gets mitigated against pit fiends. So the good burst may well be doing more damage after that's figured in. I'm thinking the numbers actually support good burst.
I'd be happy to be proven wrong or a mistake to be found in my numbers.
For those who aren't clear on what's being compared:
Good Burst: 1d6 + 3d6crit (4d6 for x3 crits, etc...)
Acid Burst: 1d6 + 1d10crit (2d10 for x3 crits, etc...)
The difference in damage on a crit is significant for an x2 crit weapon. I think its important to do the figures for each weapon in question and not just apply a blanket statement. Haven't done the math but I could see a greataxe perhaps favoring the holy more.