Your litmus test ist flawed: 1. Nitpick: What if all co-founders meet the criterion (i.e. the project would instantly die if he left)? Are all CEO's then? 2.

Your litmus test ist flawed: 1. Nitpick: What if all co-founders meet the criterion (i.e. the project would instantly die if he left)? Are all CEO's then? 2. Instant vs. delayed death: Lets say if A leaves, the project instantly dies - and if B leaves, the company will die the next 6 months if no replacement is found who is just as good. Who is more important? What if the skills of B are the leverage you depend on to become successful and stay competitive? And with 2) you are right in the middle of the discussion you want to avoid: Who is worth how much, who works harder etc., which is just distracting because nobody can tell for sure, and endangering your company because it hurts morale. That's why I agree with Joel to just split equally. And as joeag has pointed out, since it's vested, co-founders that really turn out to be useless won't get a large chunk of the company anyway.