In fact, earlier this year I finally replaced my 14-year old Zumo 550 with the latest Zumo XT and it's an amazing piece of equipment — the best dedicated GPS out there, period. I hardwire my bikes and keep a RAM mount on each, so I can quickly move the XT between bikes. Since using the Zumo 550 on the Great Divide Ride back in '07 I feel a little naked riding (or driving) without one. Adding an auto mount allows me to have the same great navigator in rental cars when we travel.
And now it's on sale, which is a rare event. $400 for the basic unit at Amazon, GPScity and Garmin.