As a follow-up, IMO the setup with 4 druids as combination caster/healer is great for stacking tons of HoTs on a tank but sucks for just about everything else. Fights in heroic gundrak were taking about 30% longer than with just 3 Moonkin and a tree, and I died on trash a few times due to the sucktastic armor of caster form. Not to mention having mana issues where I didn't before.

Enjoy trying it yourself but I think I found out what I wanted to know about it and will definitely not be using that setup.