Hey, I'm wayyyyyyyyyyy outdated in my GPS (Garmin GPS III Plus) and I know that, so as I start to look at this century's (LOL) models is battery "life" an issue. Mine is reliable however a real battery eater!
yes, the touch screen units such as the Oregon tend to eat up battery much faster. If you are looking for long battery life I would recommend a Garmin GPSMAP 60CSx or eTrex Legend HCx
No, I haven't tried an update in years. I don't believe that Garmin even offers support for that unit any longer. I will recheck that though; good point. Thanks.
my garmin oregon 450 is very temperature sensitive. if its warm to hot outside the batteries will last close to their advertised time. and i have found no big difference between lithium and regular good brand alkaline. the colder it gets the less battery life i get. during late fall and winter i keep the thing "inside" my layers of clothing to keep it usable longer.