My husband and I would like to install the KOHLER K-45209-CP HydroRail -R Shower Column in our bathroom. It is a tub/shower. We are doing a complete gut remodel. We would like to set up the shower so it looks like pages 4 and 5 in the brochure below (hydrorail, shower head, handshower, diverter valve, and spout).

http://www.us.kohler.com/webassets/kpna/brochures/HydroRail.pdf

Our problem is that the technical advice people at Kohler keep telling us that this set-up will cause problems, specifically back pressure. They say we need 2 transfer valves. But we thought the whole benefit of the hydrorail was that it contains the valve already!

Has anyone installed this product or is anyone familiar with it at all?

Thanks so much for any help you can provide.