Idk, I took my 4 Ret + DK team in with 5 Guildies, and just roll main spec, with everythign else open roll. The last 2 pulls are amazing since there are so many adds.

DK+ 4 Rets have all the CC under control, and basically as you get further, the trash gets better and better (easier to AOE)
So 10 people will get everyone more epics per hour.