If anyone is interested, here is the Transolid ADA shower, installed in my home. Click on the pics to get them back to full size. Houzz crops them.
Roll-in ADA shower floor with a trench drain. There is a regular drain under the square of solid surface material above the center of the trench. There is also a 1/2" dam that directs the water to the center drain. No problems with the pan over flowing yet, but I do have a floor drain in case that happens.
See the slightly darker square in the floor tile, about 18" in front of the walnut vanity leg and 18" to the right of the toilet? That is a drain. The entire floor is another shower, sloped with a Kerdi shower product, covered with Kerdi waterproof membrane to about 5" up the wall (behind the baseboards). If my shower overflows (or toilet does or sink leaks or washlet hose develops a hole) my house is not going to flood, because all of those wet things are within the territory of my floor drain. The toilet is shimmed level with plastic shims.
My rain shower head is in the center of the shower, so I can move freely under it. The two LED lights I had added keep it bright in there.
Q