So....you can activate Siri via the button on the motorola device and use its microphone, but audio from the phone (siri, calls, music, and all) plays through your hard-wired connection between the phone and car (3.5mm, sync cable)?
If so, that's a winner right there.
After further examination, it looks like the parrot kits require tearing apart the dash and installing hardware behind the scenes. Deal breaker.....I already have the phone wired in, I just need a way to activate siri remotely....THATS IT.
If you're looking for a Bluetooth button that activates Siri, but leaves all your audio going through other channels - stop looking, it ain't gonna happen. Bluetooth pairing sets up a "Profile" that does not distinguish between control & audio, so if you pair a device up to control the phone - that device is where the audio is going to go (by default - once in a call you could switch it on the phone's screen, but that would defeat your purpose).