I think you have a good strategy for bringing heavy armor back into usefulness and balancing it against evasion light armor wearers. However, I think the difference in PRR listed here needs to increase to make it actually effective. The difference between heavy vs light is only 30, which is very minor compared to the power of evasion.
The example you gave is based around shield bearers. For a heavy armor wearer without shields, their gains is actually very minor.
Somebody did a breakdown of what it takes to get around 300 PRR :
However, the above assumes somebody with at least 6 paladin levels using shields and a ton of past lives.
For a non-paly 1st lifer wearing heavy armor and no shield, we end up with :
45 from heavy armor
BaB bonus (24->30+6) from heavy armor
30 from items
20 from LD Improved Combat Expertise <-- requires twisting from ED + combat expertise feat
20 from Sentinel core stance
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145-151
Damage multiplier = 150 / (150 + 151) = 0.50
An equivalent light armor evasionist will have :
15 from light armor
BaB bonus (24->30+2) from light armor
30 from items
20 from LD Improved Combat Expertise <-- requires twisting from ED + combat expertise feat
20 from Sentinel core stance
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111-117.
Damage multiplier = 150 / (150 + 117) = 0.56
Difference is not really that big.
When it comes to evadable damage, the heavy armor without shield will not get any bonus defense.
I would suggest increasing the armor PRR bonuses to make heavy armor truly useful without relying on a shield. A mere 30 increase in PRR (over light armor) is not enough.
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TLDR version : Difference in PRR between light armor and heavy armor is too small. For anyone not using a shield, light armor evasion build is still the way to go for survivability and heavy armor still wont make the cut. Please consider increasing difference.
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