You'll be just fine. It really depends on the tank for most of these heroics. The hardest one I thought was Shattered Halls because of the non-stop mobs. They have to pick the adds up before the healer gets smacked. I'd advise trying to find a pally for H Shattered Halls if you can. But I did it with a pretty geared warrior, so its all possible.

Just be careful about AoEs in heroics because you will die really fast (unless you iceblock). You really want to sheep more, rather than AoE.