Seems solid enough you have a tank, healer, 3 dps, offtanking, some CC, ecellent transport.

I would go with pally tank, restro shaman healer and 3 mages for dps but thats all just preference. Mine might have a bit better dps CC and simpler healing but yours has better offtanking and ritual of summoning cannot be understated.

DK is click intensive, I would not add a DK to your group as your offtanking seems solid with two pets.