I have several questions regarding the installation of Rohl thermostatic and volume control valves. Is it necessary to have 3/4" pipe coming in to a 3/4" valve if there is not a big concern for high water volume? Aren't there less expensive thermostatic valves that have a volume or pressure control built all into one valve? I'm not sure I'm going to have the wall space available to fit two of each of the above mentioned valves for a tub/shower setup. Does anyone have any thoughts on the quality of these high priced valves vs less expensive brands? Thanks for any input anyone can give me on this topic.