I have 4 mages and 1 priest, but my mages just respecced into deep arcane at 40. If you are primarily using Arcane Explosion for AoE DPS it's a way better spec IMO. Theres lots of talents that give you back mana, or give you more mana. Plus the top talent Arcane Power is a big DPS cooldown that is useful for bosses. I've been farming SM Cathedral, and the boss fight is down to me just spamming Arcane Missiles, and making sure the priest doesn't die to Mograine.