I am actually considering wizard from what I saw Aloth could do in late game. Just empower the 9th level missile spell = everything dead. If Aloth can do that imagine what MC can do...
As for grimoires and respeccing. I wouldn't have a problem with that, money is not an issue anyway in this game, but respec is totally bugged, at least in my game. I tried respeccing my MC to make a better build and I lost all of the teachings I had acquired in my travels(the ones that cost 3k).