MWAHAHAHAHA!!!!! Well said...
Personally, I prefer dual mage/thief (once having maxed out hide in shadows, find traps and open locks, of course)due to faster level progression and slightly better HP.
But either way, they're better than a single mage who can't hold his own in a fight after running out of spells. They can defend themselves from magic but once combat protections are gone, they can't resist a blow from a powerful weapon. Just some hits and he's a dead mage.