I tried this, by making a new guy and providing the new toys.
Its not well balanced; all the bosses fell easily, never died, low risk until at least the mountains. I even limited myself a lot (eg only frost staff and raw mushroom food until mountains) and it was still OP.
Then mistlands the magic becomes a bit equalized there, low health and armor for an all in mage can't take a lot of abuse and is extra vulnerable to the mines. A hybrid mage (wear armor, eat only 1 magic food, give up pets and high stamina to get nukes) works really, really well.

Bottom line though, its not balanced for it, and it won't work well without a total redo of the numbers/scaling or adding low tier gear with the new system.