If you decide three is one too many, the new pitfall you have to watch out for is tiebreaking. Suppose there's a fundamental disagreement, like whether to sell out or whether to fire one of the two founders and find someone new. You think you'll always be able to talk things through and come to a consensus, but let's say you're wrong. A naive 2-person setup simply has no way to handle a situation like that -- it's paralyzing. So you need a way to break ties. And now instead of a fair three-way split, you have one founder with more power (and investment) than the other, or you have some outside party (played by Justin Timberlake, presumably) with control over your future if they like the other guy more than you.
So maybe two founders is one too many. Going with one founder shouldn't cause any problems ... right?