With the same comp you see in this video (Hpally/BloodDK/DestroLock/Spriest) we got nef to 7%, so next time we have time and we decide to 4 man content, he'll be dying .
Also- the dps requirements for heroic would be insane, executing a strategy to survive and kill all the adds needed COULD be done, beating the enrage at the same time, most likely impossible with 4 people.