I can compare the brand spanking new Garmin Edge 840 and the somewhat less spanky
Garmin Edge 1040 vs 1030 Plus: Right Now I'd Buy THIS One - Sportive Cyclist
Garmin Edge 840 Solar – Maison du Vélo
New Garmin Edge 540 and 840 leaked, set to release soon : r/Garmin
Garmin Edge 1040 vs 840: Which Is Best (For You)? - Swiss Cycles
Garmin Edge 840 Bundle - GPS Bike Computer GPS Cycle Computer
Garmin 840 vs 1040 [Both SOLAR Edge Editions]
From Wahoo (temporarily) back to Garmin: my review
Garmin Edge 830 Performance Bundle – Condor Cycles
Garmin Edge 840 Cycling GPS In-Depth Review
Garmin Edge 840 Cycling GPS In-Depth Review
Garmin Edge 1040 vs 840: Which Is Better (For You)? - Sportive Cyclist