I have had 2 Magellan GPS. My first was a 700 and my current is a 780. I also buy them at Best buy and take the service contract. The 700 stopped talking to me after 2 years and was replaced no questions asked with the 780. The 780 is 2 years old (i think) and has servived a pretty bad MC accident. Lost its antenna but otherwise unscathed and functional.
I am however disenchanted with Magellan service and support. They dont seem to update their maps for this model and other updates are very expensive. I think my next GPS for the car will be a garmin nuvi. My 07 GW comes with a built in. I assune you want to use the Magellan on a bike. If so, I was never real sure / secure with the magellan mounted to the bike and in fact it did let go but fortunately landed in my lap. It is also not weather proof. Used a zip lock bag once. It is also a bit hard to see in the sun on a bike and I never tried to add it to my helmet sound system however I could hear it at 60MPH with a helmet on