Ari, aside from legal issues, I think it mostly depends on how hard the installation process is going to be. If you manage to design a very small PCB which will use bluetooth, can be fit inside radar and needs only three wires to solder (DGND, VCC and LED's anode), then you can easily get some users, especially in the Valley where ppl love gadgets which they can create or expand themselves :-).

BTW. For those who are afraid of openning up their detectors you can easily desing a special version which will hook up to the LED using photo-resistor. I.e. a kind of device you stick up to detector and put its sensor over detector's LED.