Nice work sthar, sounds like you are off to a pretty good start with an interesting setup.

I'm currently enjoying a mixed melee team in WoTLK, but the team i'm entertaining for Cataclysm is:

Holy Paladin
Shadow Priest
Destruction Lock
Frost Mage
Balance Druid or Elemental Shaman

My focus will likely remain in 5v5 Arenas, but I will definitely be putting plenty of effort into rated BGs as well! With caster teams, I consider the frost mage a key player to the teams survival while the other classes still bring some clutch anti-melee tools ((Ex: Spriest disarm is pretty handy in current game for dealing with brostorm)).

The Paladin could tank and the priest could cover heals for 5man dungeons.