As you are planning to have it beneath tile, you are probably planning to put the electric elements in a layer of gypcrete or cement in the manner the manufacturer recommends, so the heat would be spread in the whole area under the tile and the carpet. The carpet acts as slight insulation, about R1, so there would be less expected heat transferred to feel on top.
It’s a good idea to have a separate thermostat to sense the tile temperature and another one to regulate the heaters under the carpet, as they transfer heat differently.
As the electric heaters would be embedded, it would have less probability of a problem than if electric baseboard on the walls was submerged.
http://www.HeatProUS.com energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.