I was skimming Reddit today and I stumbled across this post and I figured I'd toss it over here in case anyone missed it.

Basically the TLDR is this guy has done a decent amount of research around the viability of a 4 warrior/melee cleave comp. Based on his findings it may be the fastest way to clear dungeons; and level in general (even compared to solo questing at least for warriors). There's some good discussion back and forth in the comments and the link to a powerpoint he put together explaining his theory crafting in further detail.

I've been on the fence about what to play because I wanted to stick to 4 or 5 of the same class, but was worried about viability and clear speeds. This is making me lean heavily towards 4 warrior priest.