Mirror Image isnt going away
It depends on what happens at 80.
From my experience in arena, at the high end teams are highly defensive. they would let you pop your 3min of invisibility and run away. Then what do you do? Your soft and you cant really afford to let them open up on you.
Its possible, and with the new arenas that encourage straight out dps fights, you might actually do well given the right arena and teams.
Whenever you do something new, you have to realize...NOBODY knows. My guess is as good as yours....It sounds fun, maybe I should roll mages next :D