If there was a way to keep the existing forums (or some easy way of filtering), for those who might want to browse only the area(s) they're familiar with yet also present everything within a category in a single place (by default, to give the impression of activity), that would be awesome.
vBulletin does support a tagging system.. Could always utilize that as a "filter" of sorts but that would require the OP to include them. So that might not be that reliable :\
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