The biggest mismatches that I can think of involve co-founders with completely different expectations of what the company will do, different financial backgrounds and different energy levels.<p>As soon as you're 'not in this boat together' you're in trouble.<p>Other than that I certainly wouldn't let age be a problem either way or rule out people with a serious commitment to family or other dependents.<p>As for firing co-founders, that is not as easy as he makes it seem, I think that if you get to the point where you need to 'fire a co-founder' and they don't leave by themselves that you are probably better off starting over.<p>Ideas aplenty.