I don't think there's any shortage of worthwhile improvements that you could add to the site given enough time. I also suspect that there are people who would be willing to donate in order to support this site. Now that LesserWrong is the main site, it seems like a good time to ask for support. It is now clear that this project will be ongoing and you've established your credibility.

The biggest disadvantage I can think of is perhaps you would only receive a small amount of money and yet perhaps people who supported you would expect you to conform to their preferences and you might be pushed away from working on what would be best for the site as a whole. But I'm sure you have a better idea than me as to whether that'd be an issue?

Anyway, just thought I'd throw this idea out there for your consideration.