To solve the problem you mentioned about what to do once the warr has killed his mob, you could have a different follow key bound to each warr so when he has dinished his mob he can /follow and /assist another warrior. I do think that a resto druid would bring a lot to this composition but it would completely change the feel of the group as you really wouldnt actually need 4 prots anymore, could have 1 prot and 3 fury.