I tested the Active Track on mine (while wearing my new backpack) on my mountain bike recently. I was really pleased with the Mavic 4's capability. Looking forward to doing more testing soon.
My issue was when I changed the setting from braking for obstacles, to flying around obstacles. Suddenly it flew very erratically, I seemed to have little control over the flight, even when no obstacles were around (just flying over water). Not a...
It all fits fine vertically as well, I just decided to run it diagonally, since the divider strips can be configured however you want them.
The zipper pouch easily fits the charger, cables, and extra propellers.