I should have added... at the time, there were several other ballroom dancing forums that came up in the search. But one of them appeared to not be functioning, and the others were only getting a few posts per day. DF had the most traffic by far.
A huge number of people read dance forums who don't post here, so the community is really larger than it appears--impossible to know how much larger. Is it that you feel that there need to be more posts, or do you need membership numbers higher for, say, advertising revenue? And if the latter, how active do members need to be to count? If more posts, what area(s) do you think are light? Where would you like to see the growth? In the ballroom section or the salsa section, for example? Or is there a completely different issue? I have read through a lot of old threads, so I'm aware of the formerly active members who aren't posting any more, or who aren't posting a lot. Is the group of currently active posters keeping up/growing with historical trends? That's more difficult to track that just the number of members.
personally, I think FB has had the largest impact in that much of the more mundane chatter that used to happen here now happens there...not that there aren't also folks who were prolific here who have left, but that is also to be expected over time as lives change...at least that is how it has worked for me