it is a moen assembly sorry I don't know the actual valve models--no paperwork on that from the original owners and the plumber took the info I used to order the part--the part I ordered/replaced was 1423 Balancing spool Moentrol maybe something like this for the two-head control http://www.moen.com/products/T4111ORB ours is oil-rubbed bronze and it is installed with the lever at the top and the pull-out valve under it which looks the opposite of the Moen site photo the info on the Moen site says that it should turn from 'full cold to full hot' but there are stops the plumber came back out and said that when he put in the balancing spool he had opened the hot stop all the way and that if he closed the cool stop that it would not do any good because the balancing spool would basically just reduce the flow of water to make sure the balance of hot/cold stayed the same... he said that there is movement underway to basically take the choice out of amount of hot water coming through faucets and showers--that safety of not burning/scalding people is overriding someone's desire to have a 'HOT' shower... when I asked about replacing the valve/lever with one that would swing right/left to allow me to regulate the balance of hot/cold... he said it would be too expensive to actually change the control to that type of fixture because we would have to open up the shower wall--take out tile--replace it... so we are basically stuck with either setting the water heater to higher temp because that will bring hotter water to the mix and will be expensive choice or just learning to live with it like it is I plan to take a shower in the two upstairs showers and see if their water is hotter than the one downstairs--- he said that the master shower is probably farther from the water heaters--and it might be farther than the other downstairs shower by just a little...which would influence the water temp at the head... both water heaters are upstairs and closer to those showers... it is just very frustrating to find out that something we really did not consider all that much would become so frustrating... I don't take long showers--and I don't use the big tub at all--don't consider that I waste water compared to larger families or people who take a 15 min shower...so this irks me to no end-- our old house with its old shower had wonderful hot water and I am really going to miss it... Here is a link that might be useful: shower valve

I don't know if they are a waning trend or not. I chose them, not because of how they looked, but because of my frustration at having to try to keep the areas around traditionally mounted faucets clean - for so many years. It doesn't seem to matter if it's a sink mount or counter mount a 3 piece or one piece, I always got water scum (and I live in a soft water area) that eventually couldn't be fully cleaned and I hated it. I love, love, love my wall mount. If my hands are gooey, soapy, or wet, I can turn on the faucet with my wrist or elbow, etc.

if you are the type of customer that wants a rain shower, a personal handheld (that can be used to reach other places in the body a standard shower head does not reach, and also to rinse the sidewalls etc) the third would be an extra for target parts of the body etc. Most people do a standard shower head or a shower head with a personal handheld. You just have to think about what it is that you want out of your shower experience. There are also jets that can be added,,,to target certain parts of the body...they can also act as a massage....you also have to consider your water pressure as well in your home. If you do not have good water pressure then it might be best to stick to one or two combos......as the more attachments you add the more water they will need...good luck

For two shower heads and this configuration, you'll need to put a full wall next to the toilet so you can have the shower heads across from each other. The only area that closes in is the toilet, so I think it's fine. You'll still have the long side of the shower as glass, with the window providing light to the vanity, shower, and tub where you need it.