hello, i have the sena headset, i got it from here
http://www.ultimatebikegear.co.uk/categories/Intercoms/Sena-SMH10/
So far i have paired the headset up to my 660, and then paired my blackberry phone to the 660 and control the phone via the sat nave.
Making and receiving calls is easy, very good quality sound, also depends on phone signal but so far no problems.
Garmin works well on navigation, clear sound and again no problems so far.
I fitted my set to my Schuberth S1 Helmet, i had to use the stick on option, i had to make a small cut in the wind collar, also fitted the other set to mrs d's shoe raid and that was easy, just pulled out the pads and run the wires underneath.
Mrs hasn't been out on the bike yet but i made her wear it around the house to test it

again loud and clear.
I find the jog dial very easy to use and the on/off function is easy to use as well, always pairs up when switched on, so far i would definitely recommend this product.