We are redoing the shower in our master bath and are putting in a rainhead and a handheld (both Kohler). I was originally thinking of having a stacked valve trim with a thermostatic valve (volume on top and temp on bottom) and a separate diverter/transfer handle to switch between rainhead and handheld. But I've heard that you get half pressure if you choose to run both heads at the same time. So is it better to have a separate stacked valve trim for both the rainhead and handheld? It's slightly more expensive that way but if it makes a big difference in water pressure when running both heads at the same time, then I might go that route. Thank you!