Think I saw your ambi at winter romp. I've used the shockproof in the hubs of my 1300l. Haven't noticed an improvement but it is pretty hard to quantify - hence all the magic do everything special formula snake oils. I don't want to put the Shockproof in the diff because it's a bit thick and the specs seem to over promise. I'm still a bit skeptical although I've had good results from Redline products.
Using correct synthetics in 404 makes a big difference. I had two 404 radios on solid flat concrete, one with dino juice and one with synthetic gear oil. It was below freezing and I didn't want to start them up inside. Pushing the synthetic one was pretty easy. However the normal oil one was much harder to push and you could feel the resistance in the drivetrain. Also, the 404 gearboxes get pretty hot and the synthetics handle the heat better. Generally the drivetrain works pretty hard at speed so the extra margin helps - much more so than in a Land Rover.
Do not use conventional or synthetic GL5 gear oil in a Unimog gearbox! The additives in GL5 attack the bronze bearings and syncros. Use GL4. I use the Redline MT 90. On another note Lucas hub oil works great in Land Rover swivels.