A lot of companies have to deal with this. vBulletin and Red Hat both immediately come to mind. I don't see how it would set you back. You know all the people you give the source code to, so you know who to go to about leaks. And most clients won't care about the source code anyway. What's most important is that you be clear about the terms under which your code is released.
Probably should consult a copyright lawyer.