Not sure if this has been mentioned already or not, but it really annoys me when you are confronted with a character in one of those you-can't-win type of fights and later on the very same character who destroyed you in one punch joins your party and he/she is really not all that powerful all of a sudden. FFIX and Grandia come to mind here and I'm sure a few others as well.

Not really sure how that's going to work out...It's probably going to be the first RPG to use this kind of system as far as I know, unless you want to include all those games that restore the characters' HP upon leveling up.