Notes:
- Front page is tough to understand. Feel like you need a block clearly outlining the concept right at the top, and then jumping to the current projects. You've done great work with other illustrations on the site, why not a visual flow of the junto process (unless I missed it)?
- When I first saw the funding amount, it felt like kickstarter (not sure if that's a good or bad thing for you? :) )
- Project pages are really nice and clear, well done.
- I like seeing faces for projects, gives it more credibility, but what about your team?
- Recent commenters, gravatar?
As for the primary concern, tough one. Don't think there's any easy/cheap way to acquire a ton of users so early on. Think you'll just need to bridge the gap with your gut feeling till it gains more traction.
Good luck, really like the idea!