A pressure-balanced temperature-compensating shower valve does the same work and can be completely installed by a plumber for the cost of this unit. If you want to turn off the water for a military shower, you can get a valved shower head. What else does this thing do? You can’t shower in colder water than you need it to be. It won’t chase the teenager out of the shower.
Yes, you can put saddle valves on a pipe. But, they usually require gaskets and might need tightening in time. Replacing the galvanized pipe that is there with new fittings and pipe is probably the cost of the saddle valve alone. Then you have to worry about a leak.
This question looks like SPAM to me.