The problem with being allowed to make your own board is that there's way too many of them now.
I'm forgetting which one, but there was a japanese imageboard-type site that let users freely create boards, and it kind of just died because the userbase was spread so incredibly thin.
As it is, with a dedicated all things touhou board it should still be fine. but from what I've seen the conversations still become spread out across the entire board, in what I think of as the Reddit affect.
If you only have a single general to share, the conversation of the group is centralized and easy to follow. Having a board gives the options of sub-general threads for more specific topics, but I haven't seen enough organization yet.
I'll be keeping an eye on it yet though. The community doesn't seem bad.