Can you tell me what makes you want to go from Zumo 550GPS to the 660/665?
My GF ordered me the 550GPS for Xmas and its Back-Ordered..did you have any bad experiences with your Zumo 550 or is it simply the bigger screen and double Waypoints?
My 550 GPS is great. I only have one issue with it and it really isn't an issue, but just a personal preference. On the map screen when I'm following a route, the 550 GPS provides an Estimated Time of Arrival (ETA) at the destination. My previous GPS provided a countdown of remaining miles to the destination. I liked that feature better than the ETA on 550 GPS.
A friend has the Garmin Zumo 660 and I had an opportunity to play with it the other day. It has the capability for the user to chose different data for display on the map, which includes the mileage countdown.
My 550 GPS is 4-years old and I've been reluctant to update the maps because others have had issues when trying to upload the latest maps. The Garmin website even states that the update may not load completing on the GPS. Therefore, I thought I might upgrade to the Garmin 665/660 for the added features and the latest maps.
I was leaning toward the Garmin 665 because it provided real time weather graphics on the map, although at an additional monthly charge through XM Sirius. However, the more research I've done has revealed that many are having issue with the XM antenna receiving real time weather for display on the map. The only difference between the Garmin 665 and Garmin 660 is the XM Sirius capability. The only difference between the Garmin 660 and my Garmin 550 is a larger screen on the 660, currrent maps, and user ability to designate which data to display on the map.
Therefore, upon reflection, I may keep my Garmin 550 GPS for at least one more riding season, and I'll wait to see if Garmin/XM Sirius get the bugs worked out of the Garmin 665.