My opinion matters for shit, and I recognize that, but I'm sitting at work, avoiding work, so I decided I'd just put my two cents in here.

Don't know either of these guys, but what I do know is a hacker is a hacker is a hacker. Hack in one place, you do it other places. I understand the need for spot on proof/evidence of hacking, otherwise you can easily find yourself in the midst of a witch hunt, but in this case we have solid evidence, in the form of admission from the user himself and demos of his hacks on another server.

That should be proof enough. Ban this guy and be done with it. If you don't, you're basically saying 'If you're a good enough hacker to hack without getting caught, come play on IBIS!'