[donw]

I would vote for 'no'; you will spend so much time around each other, with no way to really separate your own spaces, that it will make you sick and reclusive. If anything goes south, you then have more than just a business that dies -- you have to deal with tenants, and there's likely additional legal ramifications as well.

[rksprst]

I would also say "no" for similar reasons. Your project is not his first priority and I doubt that will change once he moves into your apartment. I think that having cofounders living together is great if you guys are a couple or have been best friends since elementary school. Otherwise though, I can only see problems from this arrangement.

If he wants to move to your city then let him, than you can have weekly meetings at starbucks or something. But I'd not recommend living with a random developer that is your cofounder just because you have an extra room. Again, I can only see problems arising from this (both professional and personal).

I'd be curious to hear what you decide to do. Let us know.