"So what, if any, would be the difference between using an RCM for
rinsing & vacuuming and simply using a high-pressure hosepipe and a
Dyson
with its fine brush attachment? "
Dunno..not got 'A Dyson'

If you go to www.vinylengine.com forum and type my moniker into
author / search you will discover (#2) (also #9 etc) on the list a
thread on the Cadence Nokki-Okki-Wokki RCM.
You will find A Wealth of Knowledge/Erudition/Commonsense on the other
73 threads I contributed too to. tooo....
However, the site-owner went Quite Beserk in September 2005...and
banned me.

:-)