I'm also testing this circuit to detect if a light is on/off (So that a normal light switch can still be used with it). It does dissipate a watt of power while the light is on, but the components are small, cheap and reliable.
Castillo, your devices are quite nice, but you haven't posted a price yet. Regular light switches cost less than two dollars at the homeowner store and Insteon cost around $45 with zwave coming in at $65 and up. Both of those solutions will fit inside a light switch box on the wall and seem to be pretty reliable to people that review them.Competition is rough out there.