I can compare the brand spanking new Garmin Edge 840 and the somewhat less spanky
What's the difference between the Garmin Edge 1040, 840 and 540 cycling computers? - BikeRadar
Garmin Edge 840 Cycling GPS In-Depth Review
Garmin Edge 1040 vs 1030 Plus: Right Now I'd Buy THIS One - Sportive Cyclist
Garmin Edge 1040 vs 840: Which Is Best (For You)? - Swiss Cycles
do NOT upgrade - Garmin Edge 1040 Review
Garmin Edge 1040 vs 840: Which Is Best (For You)? - Swiss Cycles
From Wahoo (temporarily) back to Garmin: my review
Garmin Edge 840 vs. 1040 (Solar): Which One Should YOu Buy?
do NOT upgrade - Garmin Edge 1040 Review
Garmin Edge 840 & 540 Solar First Look Review: My Favorite Head Unit Got
What's the difference between the Garmin Edge 1040, 840 and 540 cycling computers? - BikeRadar
Garmin Edge 840 GPS Bike Computer + Navigation System - bike-components
Garmin Edge 540, 840 & 1040
Garmin Edge 840 Cycling GPS In-Depth Review
Garmin Edge 1040 Solar Head Unit – Condor Cycles