Off topic, but related to HP...
I also think that resistance should be broken down into: No Resistance (full damage), Minor Resistance (-25%), Resistance (-50%, like now), Greater Resistance (-75%), and Immunity (-100%).
I think that would allow for more of a progression in monster design. There could also be items and abilities which treat Resistance as one level lower.
This is related to HP because it's a method of being able to make a creature tougher without needing to rely so heavily on one aspect (HP). Also, having more steps could allow for a more gradual progression than what is used now.
This change, while small, touches many other aspects of the game. Spells, weapons, and abilities which interact with resistance and immunity could have more steps of progression as well.
I think this is related to HP because some of the game's overall progression could be broken down into smaller steps -with the goal being to broaden the "sweet spot" of play.