Given that there are several other fairly-active SE-based sites, with high-rep users, would it be reasonable to count that rep in the commitment phase? I presume it's technically possible, given that all of the sites are owned by SO (but could be wrong).
For instance, I don't have a lot of rep on SO, but have a fair amount on UnityAnswers (as do a lot of other people). So we should have a good understanding of the site mechanics, which seems to be what you're looking for when people commit.