I've been using the Garmin 376c which is essentially the same as the 276 with the addition of XM radio. I originally purchased it for dual-sport moto usage.
You can just barely see it in the cockpit area above. It has been bullet proof!
We then mounted it in our SMB.
With the ability to load topo maps and the routing features, it has been awesome. The only drawback, as my eyesight has that post-40-needs readers stage, the screen is somewhat small for viewing. I am also interested in recommendations for what is out there (Garmin) with similar features but with a larger screen.