Other than because it's easy, what's the appeal of using stereotypes to create these supposed normative behaviors? Of all the people I've met in my life, most come closer to being balanced than not. We're all extroverted in some situations, and introverted in others. Maybe being divisive makes it easier to swallow the bitter pill of unrealized potential, but it's not productive.
After seeing them on PBS around '98 The Motley Fool was to me at 19 what I'm sure Jim Cramer was to many folks around '05: a contrast to everything else at the time. I thought they were young, funny, and old-fashioned, which was appealing.
But the disjointed approach soured me on them. I feel like they wrote and spoke about value investing but then sold newsletters on timely hot picks.
So, in my mind they fell back in with everyone else contributing noise.
I think the site is good and could be great. I wouldn't sell it yet. Plus, if users love it, there's hope. If you want a few ideas, send an e-mail; I'd be happy to give .02.
I vote for Open Source. I think everyone is champing at the bit to join and share with each other, so getting it off the ground fast is best.
Also, as others have already said, this seems to be a predominantly altruistic group, so funding a better solution later won't be an issue.