Before reading the rest please note that i am not an idiot running around with a 12.7, an AA launcher and a carrial pack.
Since ArmA 3 is a game in which you play a trained special forces soldier, I think the fatigue should be slowed down in the first place. SAS soldiers are trained to march like, 30 miles with full load. And yes i do know you can lower your weapon or even put it in your backpack.
Now i know how freaking warm it can get in greece, but maybe 10 percent less fatigue would improve the game play in my oppinion.
But maybe there should also be a little more contrast in the fatigue system. What I mean with that is that you would get even less fatigue at less load, and even more fatigue at higher load. This would force players to think more about how much load they take in their scenario.