I’ve had the 2800 for the last 12 months. Bought it for using on MTB and Enduro/green lane motorbike as well as the odd geocaching.
Std battery life seems ok ( better than smart phone). Good at tracking you route with elevation/speed/distance profiles at the end of the ride.
Quick to grab gps signals and display is ok when on bike but a bit small to see when on motorbike (they now do a 3500 with 3.5″ screen).
As a bike computer I think the Garmin edge seems better with live display of speed/dist/elev gained per ride and the virtual partner training aid.
The MM is far better for navigation as you can see your location on the map, but as with most gps units you some times have to take the wrong route to then find the right route, if that makes sence.
MM2800 has a few bugs when trying to load pre planned routes from pc to mm unit and when trying to save data but the forum is very good for finding out what your doing wrong.
Would I buy another …. Yes. But I’m also thinking of getting a Edge 305 for day to day biking duties and keep the MM for longer day navigation rides.
Ade