I'm running a 5 box setup now. I'm going to do pally, 2xlock, 1xmage, 1xpriest. Currently as I'm leveling on trial accounts I have 3xlock, 1xmage, 1xpriest. For utility is the reason I picked more locks over mage, having ss/hs/paper off-tanks, more durable, etc. I had to have a mage for ports/buffs/food/water and frost line of spells.