Based on your dissatisfaction, sounds like you all will definitely break up sooner or later. Maybe the question you should ask is when is the right time to break up. From the little info you gave, it sounds like you shouldn't split up right now (as that would effect a "significant" distribution deal). After the launch, you should discuss with him how to transition things (perhaps he stays on and continues to help but at a different capacity).
if he had 100 clicks and 3 buys, then his margin of error with 95% certainty is +/- 3.4% - maybe that's enough to make a difference?
but more importantly, companies like twitter never happen under this methodology. i guess this may be sort of ok to use for incremental products, but nothing big will ever be developed this way.