I have 5 BM hunters. I used to use 2 ravagers (DPS), 1 boar(charge), 1 flyer(screech) and 1 wolf(furious howl). I loved it. I had all but birds growl on and they traded aggro perfectly. Everyone got a tiny bit hurt, but with spirit bond, all got healed automagically. Also with my mend pet and Draenei Gift of the Naaru, I could heal just about anything. Now, I changed to all ferocity pets to prepare for WotLK. Now, 2 wolves, 1 flyer, 1 hyena (50% slow) and 1 tallstrider (AOE 1 attack miss). I basically have no tank and no healer, just share aggro enough that healing done over time helps enough that no one gets hurt. Plus my pets can pretty much solo anything, I just have tap it to make sure I get credit for the kill since they die so fast.

I always wanted to do 5 locks. I don't care about healers. If you want a healer, do a mixed group. I would do them now, but already have shammies and hunters. And I want to save spots for DK's in WotLK. Maybe 5 stealthers might be fun and if they could do other things also like heal, so I would do like 5 feral/resto (about 1/2 of each) druids. Maybe 4 warriors and 1 healer. Imagine like 4 windfuries going off and having 4 tanks. Just do what fits with you, you will have to level them up. Have fun.