I have been told by other guys in different states that they are hard to come by, or virtually unknown.
As for moen, they are very flimsy because they are all plastic inside and I don't like installing something a customer could feasibly yank apart, newer Delta's seem to be that way also.
On the flip side, I worked for a shop in an area where the water was rediculously corrosive to metal and moens strength turned out to be the plastic internal parts that don't react to highly corrosive mineral content.
Welcome to the forum, get to know the regulars, pay attention.
What the others refer to as a "smitty" plate I call a "goof plate", Symmons makes one, an oval shaped chrome plate that has two screws similar to toggles that secure it to the wall and the plate is made to fit under the valves trim, it works with other valves, but you may need to cut some material from the center to conform around their trim.
Also, looks like installing this would require alotta opened wall.
I'm not seeing the advantage to installing something like this over a single handle, unless a customer has a fettish for having to play with the two handles to adjust shower temperatures...
I'm with dog Symmons is the standard in California and Nevada for anything above residential construction.
"Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony
I never lost a cent on the jobs I didn't get!
Symmons has both, anti-scald on the handle that only allows it to be opened to the point the hot mixes with cold for a setting of 112 or less (set by the plumber) and scald protection where the balancing cartridge compensates flow to the hot when flow is lost on the cold.
I fully agree with your thoughts on single handle...aside from a fettish for the oldies, it makes no sense why someone would want to have to play with the valves for five minutes first thing every morning to get the temperatures right when all you do with a single valve is remember roughly where you ordinarily put it.
Then there's the fact that valve looks like alot of wall has to be opened to get it in...single valve all you need is a plate to cover the hole.