If my startup grew past 5 team members, I would personally just move my private repos to GitHub and start paying them. Bitbucket provides a great free service, but I'd probably never pay for it.
You just might reconsider (and that is what bb is banking on), at the end of the day having to police the number of repos you can have is a pain(esp in a startup, where people are seemingly forever going off to hack away on random stuff). Sure bb isnt as pretty--current redraw notwithstanding--but unlimited repos is very handy indeed. just saying. Inline commenting was missed (we moved from gh to bb a few months ago), but i see that has been released too.