MrJR;
Our experience with the "self-contained" pull behinds as you are describing, is that they are designed for what I will refer to as a "quicky clean; or, cosmetic clean" at best. They will not deliver a through deep cleaning or rinsing of the fibers. Using these in homes one will find that they are very hard to move around (weight and size) and therefore, the Operator will untilmately end up using a wand off of this style machine anyways.
My advice: Purchase a great quality HWE and be done with it and keep your great reputation in tack!
very best;
Ed Valentine
cross-american corp,