I've just bought two Sena intercoms, one for my Shoei Neotec 2 and the other for my wife's Schuberth C3 Pro.
Fitting to the Shoei was easy, the Schuberth less so. I had lots of set - up problems (caused by me, in the event) and spent an hour or so talking to Sena on their chat line on the computer. A very patient lady guided me through it all in real time (i.e. she would provide an instruction, I would carry it out and then we would review its effect) until everything worked.
I've tried both sets a few times since, and so far they have remained "paired"!