I have a Sena 5 fmh thingy. It works well, I just wish it was louder and the sound quality was better, very little bass....but I guess you can only get so much out of small, low profile speakers.
Will probably upgrade to the 10 at some point and put the 5 in my SO's helmet.
(I mainly use mine for listening to music, and taking a phone call now and then. Haven't had the chance to pair with others and communicate really)