I've got a set of Chatterbox XBi2 units so can add a bit. The units themselves work well and have been out long enough that I got them separately off Craigslist for $100 each. I can get that out when selling them, too, so have a lot less invested than most comm systems would be. They've had no problem doing the bluetooth thing with each other, my Blackberry, my son's phone/mp3, etc. I can plug a patch cable from the MP3 into the XBi2 for music or use a BT dongle. The times I've tried the phone, people were surprised to hear me say that I'm on the bike. The intercom works well if within visual range for bike to bike.
People knock the bluetooth devices in having a battery range that would be undesirable for long distances. These things go about 5-7 hours, depending on how I use them, and are easy enough to swap that I don't even have to remove my helmet. That's 10-14 hours. You can not charge and use a unit at the same time, but you could get one of these and plug in the spare unit:
https://www.denniskirk.com/jsp/product_cata...;utm_medium=cse
One thing I really like about the XBi2s is that the headset is not attached and the headset jack on the intercom means that you can change style of headset. I've got an open face and full face headset and have found that if the full face headset is installed, the chin bar of the Arai Corsair is too tight, while the Shoei is OK. With the Arai, I have to remove the velcroed mic before putting the helmet on and off or the mic will catch on my chin. Because of this, the open face headset is actually easier to use for the full-face Arai, because the boom mic is easy to move or push out of the way.
The headset jack is a TRRS, similar to the one on an IPhone, but wired differently. I've tried versions of IPhone type earbuds that have a built in mic and haven't found one that plays nicely with the Chatterbox connector. Plus the mics were not wind-protected well enough.
Which brings me to the down side of these and most others. IMHO - all helmet speakers suck eggs. You just can not beat earbuds for music and to cut road noise, instead of adding to the noise. After the honeymoon period with the XBi2, I went back to earbuds for just listening to the radio on my commute and use the XBi2 for when I'm out with somebody. No syncing the bluetooth for just riding home, no trying to turn the little speakers up enough to hear muddied music, no microphone issues.
The next thing for me to try is the Chatterbox "Student Racing Headset for XBi / XBi2 Communication System" (Model number CBXBIRSHS) I think that it's going to be the nice intermediate step that has a boom mic from the open face helmet, and will allow plugging in any earbuds for the sound. Here's a photo:
https://classiccruiser.com/product.asp?item=847590