Scott,
What's wrong about using the "Miscellaneous" Forum?
Just the fact that it comes lower in the list?
Quite a few people posting here seem to be unsure where to place a topic, often defaulting to the DSI or DSII forum based on which boat they own.
I suspect that dividing up the site will probably not help - not unless there's a moderator that monitors the site and moves topics around.
Otherwise, adding more forums just increases the number of places you need to look for misplaced topics.
Look at "rigging" vs. "sails" as an example. Where would you expect to find the discussion of the Doyle UPS?
If you go to the homepage there's a list of 5 recent topics. These links drop you directly into the forum without showing you the layout of the whole place. Many times it seems that people just create a new topic where they have landed from reading some other active topic.