In short: I have a potential co founder, which is something that everyone seems to say is good. The problem, though, is that I don't think this guy is perfect (he may well think the same of me), for various reasons. Ok, no one is perfect, but I know people that I think would be "about as good as you could get" (unfortunately they aren't available), and this guy doesn't measure up.
Better to strike out on my own, or throw in my lot with someone who's perhaps not the right person?