My Zumo 660 came off (due to human error caused by a shoddy design) as I was entering the highway in St. Louis. Wife jumped off her bike, kicked it out of the way of oncoming traffic, as a result it was scuffed tremendously. It was fully functional for the rest of the trip but has since been replaced by a Zumo 595. I will be sure to connect (and check) it before journeying onward.
FYI - I also rigged it the new unit into my ignition switch via a replaceable relay.