This is a thread on the beta forums that I found interesting. Since not everyone from here reads (or can post in) the beta forums there may be better discussion here.

Their experiences seem to be based off of heroic modes with the most recent beta patch (and some last patch).

http://forums.worldofwarcraft.com/thread.html?topicId=27497536220&sid=2000

They made really good points so I don't really feel comfortable trying to sum them up since I have not done the encounters. I HIGHLY suggest you read the first, second, fourth and 6th posts (the ones by premonition players).