just bought the zumo 660 and was suprissed to see there is no security device to stop the mechanism from opening whilst riding. my previous zumo 550 had the small fiddly screw. i am know considering the touratech lockable mount as it locks the zumo into the cradle. question is, do i really need one or is the unit likely to jump out of the cradle if i hit a pothole or go over a speed hump a little too quick ???