What about the 21,5"?
I'd prefere the smaller size since I'm used to "work" with 2 displays and I'm no hardcore gamer at all - expect me to play Diablo3 but... dunno if there will be anything else.
Is the 27" way better in performance (for games) than the 21,5" when playing with native res? I know the 6970M is stronger than the 6770M but 1440p could eat this advantage up?
Depends on the Game.
SC2 -> No
Crysis -> Yes