I've been musing about the Area 51 commit percent today, and I have a question. The stated goal of the system is to make sure the sites that launch are pretty sure to succeed, as I understand it.
But right now, with requiring so many 200+ rep users at another StackExchange site, proposals that are overlapping heavily enough with the existing sites to draw high reputation users. Which can be contrary to the idea of having an expert-driven site, if those users are tangental enough to the proposal topic that what you're actually waiting on is a large number of "interested dabblers who happen to be computer pros".
My question is, why not have the % commitment be an average of your three metrics, rather than a minimum. If we say, based on your weights, that a 200 rep user is 2.46 times as likely to participate, a site having to attract a larger total number of users to off-set a low number of high-rep users would likely have a similar "expected participation" rate, and may benefit from being able to exploit a large surge of initial users drawn from active recruitment, instead of invariably losing people as time progresses trying to accumulate high rep users.