Moen Lindor 1-Handle Chrome Tub and Shower Faucet

We had installed this set in our old house last year, and liked it so much that we bought another set for the house that we just moved into a couple of months ago. Installation instructions, however, could use a little bit of clarification. They clearly say that when installing the full tub set, the valve should be 32" above the tub floor, and when installing the shower-only set, the valve should be 45-48" above the floor, but with no explanation of why they are different. Only after installing the full tub set with the valve at the 45-48" of the shower-only set, and having water flow out of the shower when filling the tub, do you read the troubleshooting instructions and find that they consider a 46" height difference between valve and shower head to be critical to preventing that. That is the height difference that would happen if the valve was placed 32" above the tub floor, as the instructions mentioned, but it would have been nice to have that critical piece of information in the instructions themselves instead of just buried in the troubleshooting. We are now faced with the possibility of having to move the valve down 12" and repairing the old valve hole in the tub surround.