As I wrote in "my" set of forums there are ca 12 forums of which maybe three could go as they are not well delimited and so get posts that ought really to go in one of the other forums.
Losing those would be a benefit but minor. (not "significant")
However a re-organisation would always be of some benefit. I have recently acquired a forum in the SharePoint set that is way off-topic and which should never have been placed there (it's for a beta System Center Management Pack).
It's proving impossible to get the (Microsoft) people who created it as a SharePoint forum to move it to a set of System Center forums (of which there are many - a good place to start your re-organisation perhaps as there should not need to be different *sets* of forums for the same product) so a complete re-organisation may have that as a good side-effect.
WSS FAQ sites:
http://wssv2faq.mindsharp.com and
http://wssv3faq.mindsharp.com
Total list of WSS 3.0 / MOSS 2007 Books (including foreign language)
http://wssv3faq.mindsharp.com/Lists/v3%20WSS%20FAQ/V%20Books.aspx