It's an interesting thought.

Cleared deadmines at 18 on my mage team today. Was a bit of a struggle but some of the mobs are 2 levels above me and my characters are half naked so I imagine it will improve. Definitely not as forgiving as my warlocks. One mistake and a mage drops quick. When I get cone of cold at 26 to cycle with frost nova so I can AE kite effectively it will make a huge difference.

Still not 100% convinced that this comp can manage DM but we'll see. If nothing else, it'll be handy to having mages on 4 of my accounts I can summon to provide portals and water for my locks.