Hmm, good, but at the very least, he would have problem with blood supply (remember, we're talking about severed limbs here, which mean a lot of blood is wasted for a while). In short, he can't regrow anything if he don't have sufficient material. Make this one of his limitation.
I dunno, maybe the Twin also a decent pilot? (B ranker) God knows, we haven't learn why he can pilot I.S. yet :3