I'm a post version 1.2 level 50 Sorc Healer, I have come to realise I am playing a PvE spec, Like some people have said previously if you are standing still your a free lunch, but I only have 1 insta cast heal and I have my bubble, so to effectively heal I need to LoS which is not too hard but once I get marked by the other team it's goodnight.
But the best strategy is to get outa melee range, if you stay and try and out heal you deserve to die, first point of call when I get jumped on is to Stun/Slow - force speed - Then either find a nice little hole to hide in or find someone who might protect me, but when puggin it's highly unlikely.
I heard about Sorcs/Sages being OP and getting nerf'd around 1.2 and subsequently read alot of QQin from them, learn your class, your not a "Tank" any more, you can still out perform people if that's what you wanna do, but your a support class.