I run 1 team at the moment with prot pally tank, resto shaman, 2 x arcane mage and a destruction warlock. Using Mercurios DPS 2-step macros I have no aggro issues to speak of.

Arcane mages are good macroable DPS but they are somewhat annoying imo, arcane missiles break follow and turns the mage towards the mob wich makes it harder on movement sensetive fights as your slaves dont move clumped together.

Mixed teams are fun and its handy to have all/most buffs/cures and other utuilities (portals, food and whatnot).