Scott,

There had been an extensive article on making homemade ones.
The author had been interested and investigated them a great deal.
Then he got a nasty bronchial condition where he could not work with wood again.

One of his comments was that it you add a cyclone (a good one) to an existing vacumm source, the volume of air would be reduced (when everything was clean) but you would eliminate 90+% of the particles going into the filter.
Of course, if the original system is ready for the filter to be cleaned or replaced, the volume of air will be much lower than adding the cyclone to a clean filter.

You probably always win with the cyclone over all.

Just found the article: http://billpentz.com//woodworking/cyclone/index.cfm

A strip planked cyclone would look great in your shop, if you post pictures :)