I've been looking around at the different bluetooth systems and none really were what I was looking for. I finally looked at Collett Communicators. I had a set years ago and they were amazing! The only reason I sold them is I was without a bike for quite a while and needed money. The problem I have with the new bluetooth headsets is with multiple riders. With the scala, if you have 4 riders you have to pair this one to that one and the others to the other and it relays in a certain sequence and blah, blah. The Collett uses 900Mhz radio frequency and you can have an unlimited number of users. There's no pairing to the other units, they're already set from the factory! Yes, the scala set is paired but, only to the two units in a set. They have three channels built in and support stereo bluetooth. The one I've been looking at is the RaceFone2 because it has a detachable microphone instead of the standard boom mic which works better with a modular helmet like I have. They are pricey but, they have a great warranty and it's doubtfull you'll ever use it! Here's a link.
http://www.collett.mb.ca/products.html