I have a headroom problem, and JDS is about all that will fit.
Has anyone used one? They claim to have a different impeller design that
gives better suction at higher static pressures; if true, that is good since
I will be using it with a 4" hose. Sadly I just don't have the room for
permanent installations; all my tools are mobil.

The JDS salesman says that the 3hp would be overkill; for one tool I would
get all the suction I could use from the 2hp. But I don't want to buy a
small machine and have to upgrade latter on; that is just false economy. I
have done that a few times in the past (okay, many times...) and regretted
it. Plus, it seems to me that a 3hp has to perform better than a 2hp on
something open like a CMS. Any thoughts on this issue?