Interesting that this thread was revived. I just finished a 7K mile ride with both a Zumo 550 and a Nuvi 765t.
The Nuvi is adequate even in sunlight (barely) but the screen cannot be covered with anything. On the first part of the trip the Nuvi was in a Ram Aquamount and with the extra layer of frosted plastic (the Aquamount front is a rubber- like plastic) I simply could not see the screen during daylight. At night it was OK but using the touch screen through the Aquamount plastic left something to be desired too. So I bought a Ram motorcycle mount which is basically a plastic ring that surrounds the Nuvi but leaves the front and back bare. I covered the back with cellophane tape and wrapped electrical tape around the entire edge making the unit basically waterproof. I put a coating of axle grease on the mount contacts and where the cable enters the Garmin mount. I did ride through a lot of rain and the unit didn't suffer in any way; I assume it really is waterproof but of course do not know for sure and I would not submerge the unit like that.
With a bare screen the Nuvi is sufficient and virtually equal in performance to a Zumo 550- both recalculated at the exact same speed but I think the Nuvi responded a bit faster to the touch screen than the Zumo did. A couple of nice features of the Nuvi that the Zumo does not have are the satellite screen as well as the 'where am I' function. The satellite screen is certainly not necessary but it is handy waiting for the GPS to find its position, basically to make sure the unit is working correctly and just does not have a fix yet. The 'where am I' function is outstanding though and I ended up using it to mark all my fuel receipts as to were I was when getting them- the longitude and latitude are more than close enough to track down exactly where on the road I was later given a PC- it is faster to write down the lat. and long. than it is to write down the city, state and locality.
Otherwise the Nuvi had all the functionality of the Zumo and given that I use both the MP3 player for music, and the Bluetooth connection to connect my cell phone the older series of Nuvis are about the only ones that do that. No current automotive GPS offers both MP3 and Bluetooth to the best of my knowledge. The new Montana series from Garmin does, and they look fantastic but again we are back to a very expensive unit. The older Nuvis are getting to be in short supply though so soon enough they may not be available at all- they have not been available new for some years but there are occasionally refurbished units for sale.
Brian
