I recently got back from a bike tour (so I was continually going to a new place for me, but on major roads most of the time). I have an Edge 705.
The Edge 705 is pretty accurate as an alitmeter, but I decided to tick the Elevation Correction option in Garmin Connect as I perceived that was more accurate given that I was on fairly major roads almost the entire time and figure the elevation correction feature will have good data compared to the Edge's calibration.
Question: which is likely more accurate, the original elevation gain data from the Edge unit, or the "corrected" data in Garmin Connect if the correction feature is enabled?