Ugh, I ran into this last night, an ICC geared dps qued as a tank heroic nexus. I am running heroics on my new holy pally, and I had to spam heals like crazy to keep him up. As soon as I got silenced he dies, on first boss he gets 2 shotted and dies. During all of this he is linking and bragging about his dps (rolls eyes) Thank god he leaves after I went off on him and I get a low geared tank, had no problem keeping him up. In fact on second boss, we some how pull 2 packs with the boss (8 mobs plus boss total) and I kept the tank a live through the whole thing.
Armor got nerfed guys, you can't DPS tank maybe on my main healer I could keep up a crappy dps tank but I rather not and that toon has no reason to run heroics.