I run a J&M audio Integrator. It can do "leashed" intercom, will amplify any thing you can dump into an 1/8' stereo jack, has separate inputs for helmet speakers, mp3's, phones and radar detectors or GPS. It priortizes the inputs, music being the last and radar being the first.
The helmet headset is separate and the lower priced one is not bad at all. Audio quality with the voice activated microphones is fantastic, the speakers are a little subjective to judge sinces it's used on a really loud ass bike. Installation of these is possible on just about any helmet with an exacto knife, steady hands and some bravery. The installation ended up looking very clean on mine, you don't cut any material ofrliner, just the inner hard styrofoam by your ears to make pockets for the speakers.
I have never had any problems with it, and mostly use it to jack the volume on my mp3 player up so I can hear it, but originally bought it for riding with my wife...but she talks to much so I told her it was broken:rofl_200:
I don't think it will do bluetooth.
The main box is supposed to clip on your belt, but it's bulky enough it's really better to put it in a tank bag.....about the size of 4 packs of cigs stacked 2 X 2.
It will run all day long on a set of batteries, or you can buy the rechargable battery for it...$$$