I have the Garmin Edge 305 and just bought the Edge 500.
My edge 305 was having problems holding a charge for even the length of a short ride, so I had to send it back for a new battery. It was 2.5 years old though.
The 500 does stay charged longer than my 305 ever did, even when it was new, and the handlebar mount is a lot nicer... I don't see much difference other than that.
(My 305,, even when new, never stayed charged for 12 hours though. I also have a forerunner 305, but you were asking about the Edge, I believe.)
“The only way to keep your health is to eat what you don't want, drink what you don't like, and do what you'd rather not.”
| December Minutes: 406