I agree w/ the above: it depends on how you organically work out who does what. Also important is the stage of the company. If it's seed investment, I'd be open to a lot of creative give and take, sharing of roles. Later on (Series A, etc), I'd want more of a sense of discipline too: clearly defined roles, though not too rigid. And clear decision processes. Also, if you're not really an operating company yet, it's unclear what the COO does. Might be better to have someone who wears an "interim CFO" hat, so investors have a comfort level someone has financial expertise (if they do!), is watching costs, etc.