I use them as well. They're actually safer than the reptile UTHs, as they're made for human use and are subject to stricter controls. Just examine the pad regularly for signs of deterioration, as the instructions indicate. Also, don't set anything heavy directly on the pad. I use mine under a 30 gallon glass tank, and I have the tank elevated about 1/2 inch on wooden blocks, so it isn't resting directly on the pad. Light sterilite or tupperware bins are probably fine--for bigger ones with heavy animals in them, I'd elevate the bin on blocks or something so it isn't crushing the pad.
UTHs are also supposed to have air flow under the tank when you use them, so this isn't any different.