Might I ask what the usual message frequency is for a mentor? I'm used to giving GM help (new members seem to single me out as some sort of know-it-all miracle worker...) so I'm not entirely opposed to being a mentor, I just want to get an idea of how much commitment that translates to.
I see myself as a relatively standard member (in that nobody recognizes my username for much), and after about a year and a half on the list, I have had 4-5 requests. At the moment I'm only mentoring one user on a project of theirs.
So basically it's not much of a commitment at all for me, but your case may be different because, well, you've made some great games and people know that.