Prof x is op. I don’t know why you wouldn't want to take him up.
Never regretted it. Big health pool, increased combat power rate, a 6r3 does a hell of a lot more than 5r4Edit: I have apoc and colossus both at r2 boutta be r3, got arcangel at r3 and prof x. Don't regret it at all. Good mutants go up even with a stacked roster.