What I'm really looking for in a headset is an experience like on a college "road trip", where everyone in the car talks to each other and can hear the radio/music/GPS/... but in my world we're all on separate motorcycles with bluetooth headsets. So maybe one bike has the tunes, another the GPS, and yet another a radar detector, or maybe they're all on one bike. Then each party can have their own phone which can tone just them (like call waiting) so they can say they're dropping out to take a call before they accept the call.
The Scala Cardo G4 has the ablility to simultaneously communicating with 2 different bluetooth devices. It can be used to "conference" intercom with 2 other helmets, or to allow the "passenger", i.e. helmet on chanel 1 connection, to be able to hear a phone conversation. But it is severely limited at the same time, since once you're talking to 2 other helmets the GPS & Phone can't interrupt.
So it must be possible for audio on one channel to be copied to another channel, which seems to me would make it possible to have background music/GPS/Radar audio during a conference call so other party/parties can all hear it. It would only be limited to the number of simultaneous connectin the unit could handle. But then again, if another headset receives the audio and is connected to more helmets it would be forwarding the audio too, so seems like the group size could grow.
I can see how if a man in the middle drops out it could split the group so it is probably best to keep the group size down. It would be great if something like the SMH10 with 4 connections allowed 5 headsets to be fully interconnected so ther is no disconnect no matter who drops out whether from taking a call or getting left a little to far behind ... eat my dust :P