I had my Edge 810 in use for 9 years, but the battery holds only 5-6 hours now so I bought the 840 last week.
For a longer Brevet this weekend I wanted to be save so I used both.
My 810 recorded 5,443 meters the 840 showed 6,230 at the end.
The gpx track had about 5,600 to 5,700 meters when uploaded in route planing tools and other participants of the Brevet recorded between 5,400 and 5,800 meters.
So 6,230 is definitively to much.
Does anyone else experienced similar issues when changing to the x40 series or do I have a defective unit?