Personally, I would use the pally as the tank (great tanks), spec the priest as holy and swap the rogue out for the DK.

This would mean that all the melee are in plate, which may help with surivability a bit. Added AOE, silences, deathgrip etc.

I think the complexity is added when you have 1 dps as melee. Adding a second DPS doesn't add to the problems. You solve your positioning for 1
you solve them for all.