The topic of this thread is around optimal performance in an MMO. Optimal performance precludes the PS3, as between the graphics and input limitations, you are always significantly behind the 8-ball. I would never tank on PS3 or accept a PS3 tank into any progression setting, because I simply don't think it's possible to play at an acceptable level on such a compromised platform.
Maybe I am a dick, but I think your ability to play a "game" however you want ends the moment you inconvenience someone else. Single player games? Fine, do what you want. A game where 3, 7, or 23 other people could suffer due to your platform limitations (especially in a role like tanking or healing, which tend to be less forgiving of error by nature)? Not acceptable.
I always struggle to understand the sense of entitlement people seem to have around their own enjoyment in a multiplayer environment. Those other party members are no less important than you, and if enjoying a game your own way makes their experience less fun, you're the jerk.