Yes I saw them Bob. Pricey indeed - more than half what I paid for Xumo. From what I can read on forums like UKGSer if the device is mounted properly the mount holds it quite securely.
on my old Garmin Montana I used to lock it to the cradle. But, it was right pita when it needed removing whereas when I just clipped it in it was a lot easier to remove - literally a second and one hand. It was definitely more secure in my pocket than on the bike when not riding.