Setup isn't always the same but the other 10 dps would be 2 fury warriors, 1 kitty, 1-2 enhance shammies, 1-2 rogues, 2 mages, 2 ele shammies.
When we started AOEing adds, we didn't think we had enough as we only had 1 Moonkin and 1 DK. Turns out, you didn't really need that much, as long as you use other classes to help out. In our case, it was 2 Demo Locks and 3 Rogues, alternating CoS between specific seeds. With Meta, locks absolutely destroy adds, even better than moonkins. Kitties are good too, but since we don't really have one... Main issue here are dps cooldowns, as it's unlikely that you'll have everything ready for each set of seeds. Usually it's 1+3, and 2 - switch some classes around to help out. 2nd set is most problematic to us due to Sulfuras Smash right in the middle, so we usually want to save some cooldowns for that part - one extra rogue, have Fury Warrior help out, Shadow Priests.