sorry to disagree 2k but I owned the TomTom and it literally (physically) fell apart, so I (for one) cannot recommend it. I have the Roadtech 660 (no XM) and it is "average" compared to a GM automobile system. Garmin uses sticky strings to link waypoints, and when riding suggests you "turn right" (or left) as you pass your waypoint. Microsoft Streets (for example) allows you to click on a spot, then click,click,click until you have a route, the last click is the destination, hit "calculate route' and DONE. The clicks are waypoints (not stops), my Enclave operates the same way. I did not install a NIM but I did buy a Bluetooth ear piece, paired it, and I get my turn prompts loud and clear and phone calls show up on the Garmin screen.
The technology is pretty common between manufacturer's so the "program" and features are worth evaluating. IF the visual screen is of limited importance to you then you might just try using GoogleMaps on your smart phone; add a Bluetooth ear piece, pair, and you have the same thing, OR buy a handlebar mount and leave the screen on (on the phone) and you have a smaller version or the same thing. Carry a zip lock bag, cover and zip if it rains (I do this even though it says "water resistant").
OWL