I have a Garmin 1030 also a fenix 5, I recently did a ride with a friend who also has a 1030 at the end of a 50 mile ride there was a difference in elevation of around 200 feet.
I did another ride by myself using the 1030 and the fenix of 75 miles at the end of my ride fenex showed 6800 feet while the 1030 showed over 7500 feet there was a difference of 800 feet, I have been in contact with Garmin support who tell me its because the barometer on the two devices are in different positions and consider these readings are in an acceptable range, they also said that the difference between the two 1030 devices was in an acceptable range because of wind difference between two riders one being further along the road. I find these answers are a bit vague to say the least when at such a high cost to purchase them, how on earth do we know what elevation is correct, no wonder people are going to different manufacturers. Has anyone else experienced this problem