Eh, while it's an interesting twist, I seriously think the feats are not exactly very usable atm.
Power attack is currently very low-utility for PCs (pretty much only a all-out focus on STR like fighter and barbarian will use it, paladins and rangers can't), while auto-hit monsters like giants/dragons (who miss only about 10% of the time even with the current power attack changes) lose very little.
I think I like the compromise in Neverwinter Nights, that the +/- be a flat 3. i.e. -3 attack for +3 damage(+6 for 2h)/ +3AC. The feats would nerfed from the 3.5 versions, but would still be highly useful.
I think that Power Attack gets hurt more at higher levels...while Combat Expertise got hurt across the board. Fighters who would otherwise take it with their ample feat selection no longer want to, and if they need it (usually for a third party feat) it feels like a punishment feat.