just an update. i installed a new avh4500bt over the weekend to replace my avh3100dvd.
all harnesses were compatible. and since my steering wheel has no BT button, i didn't need to reprogram the PAC or get a new version or anything.
i routed the BT phone mic cable to the ceiling near the rearview camera, and the USB cord into my center console. everything works great with my Droid4. all steering controls work too.
