Need I say more?
Instead of the inheritance mess, or to complement it if one just can't use it, wouldn't it be nice to have filters by db ids?
The second is to have a meta title for the filters instead of the actual url, and combine for more than one url.
Even with some issues and headaches, the plugin can still be used, so great job so far, Jeff. Please take into account usability as well, I know this is one reason you started the 3.0 proj. So thanks for listening and for the work done so far.