The ReptiTemp has infinite control, not just low med and hi. What it doesn't do is give you degrees to set it too but I have heard that the ones with degrees are not usually accurate anyways. Reaper, you must be lucky.
The only thing is, with degrees, once you know what degree to set it to it is easier even if it doesn't correspond to the actual temperature. The ReptiTemp will control two emitters and it works well as I've used the same thermostat to control two separate cages.
I'll have to get the Zilla one and try it so I can give a comparison between the two.