I can see the arguments for keeping some stuff separate, but that could still invite attenuation of discussions and attention. IDK anything about the mechanics of the site, but would it be easier to limit the new posts to just one board? Also, that might make signing in more attractive - the backlog of content means it takes a long time to load a MB page or refresh the board when you are signed in, so I only do it for specific purposes, and then sign out again to browse.