hey hey
i bought it and have already used it a few times on motorbike tours. mounting it in the helmet is no problem and the things stay in place. the communication is clear and distinct, even at 80km/h in closed helmets.
where you want to mount the talk button, you have to test yourself. i have everything in and on my jacket, so i'm not connected to the motorbike. i can't say how far they reach, because so far we've mostly had visual contact. occasionally we've also had babyphones on the devices, change the channel and it was quiet ;)
compared to helmet systems, the whole thing can also be used as a normal outdoor device. a clear advantage for me.