My opinion, if it is worth anything...
GPS units are getting cheaper and cheaper. For those that use the run of the mill types, buying a new one every two years is probably the better option than a lifetime subscription on one model for updates.
I paid $399 for my Magellan 4250... It broke inside of 3 months. They replaced it with a new unit that never worked right. Bought a newer, and more advanced Magellan a year later for $150, less than half the price of the last model... it died in two weeks... replacement never worked right either.
Bought a GArmin 1300t for $239 last September.... It is still working just fine! I can now find the 1300 for as low as $129.
I'm now getting ready to get a DROID based phone... That will use Google maps for navigation and I will see how good it really is... Probably serve as backup.
Now... I do want the Zumo 665 which retails for $999 with some sources selling for $800+.... If I invested that much into a GPS I'd most certainly buy the lifetime updates as long as I could buy an extended warranty on the bugger.
It is all math eh? :2thumbs: