Was asking myself the same question. In the end I decided to go with the newer u2713HM; I have several Dell monitors at work with varying degree of AG coating, and it really puts me off (the off-whites are horrible). I read that the u2711 has perhaps the worst AG coating of them all. That, plus the fact that its 2 years older made me make up my mind.
So far I can say that the u2713HM is one fantastic monitor. If you're worried about AG coating then don't - its perfect on the u2713HM.
I bought it mainly for gaming, and it does that exceptionally well - ghosting/trailing is pretty much non-existent and the response time/input lag are extremely minimal. I can't really feel it even when playing FPS games. The high resolution does strain my 670gtx in some games (looking at you crysis), so there is that to consider as well.
I would not fully recommend buying it though. At least not now. While being a fantastic monitor overall, Dell have not yet ironed out a few problems that seem to plague it. I got somewhat lucky; my one only has a bit of back-light bleed and two unnoticeable stuck pixels in the right lower corner. I'm sure you have read other people's woes regarding cross hatching/severe back-light bleed. Best wait a few months IMO.