I have the Zumo 550 and XM radio as well. It not only lets you preprogram your routes, but also keeps track of your gas consumption, reminds you when you are getting low, and lets you easily search for nearby gas stations, hotels, restaurants, etc. With the bluetooth connection to your cell phone, you can even call ahead to make reservations or whatever. I wouldn't be without it for trips. It comes with a motorcycle mount as well as a car mount and can easily be switched between the two. HD is selling a branded version, but the non-HD version is virtually the same and is much cheaper. They're coming out with a Zumo 650 soon, so the 550's will probably come down in price.