Andy, I don't think you have much to fear in the way of competition. Bearfilms is head-and-shoulder above any potential newcomers. Besides, competition is ultimately healthy.

But on the other hand, a few thousand dollars for a good domain is not really going to make a significant dent on your bottom line. I would keep it and build feeder sites, a blog, a TGP... something to drive traffic to BF. In the long run, that would provide a lot more value than selling it.