The GE Add-On switch does what it was designed to do: dim the lights if it's hooked up to a 3-way circuit or just plain on/off function. It is easy to install - ground, traveler and neutral (no power , no load). No need to introduce it to your router or bridge.
I have several of these switches now for a couple of years, and they work perfectly with my Samsung smartthings hub. They appear to have excellent quality.
Please note that these are not stand alone switches, but add ons for three and four way applications requiring a GE smart switch in the circuit.