I'm with perry too. . .
Something another niche site I (not very often any more) frequent did was to open another forum..
The main site was about anything in relation to the core subject (rabbit hunting, in this case)..
When popularity set in and the value of the community was realised, it was hard to keep all posts based around one core subject so another forum was formed for everything else..
It sort of works over there and, even if for a second, could be worth a thought?