Why would you ever have soldiers below 80% or even 100% carry weight.

[Divisible by Zero]

Unless i am missing something there is no reason to EVER run soldier below 100%  Would it not be reasonable for there to be a counter point to the running over weight time unit loss? For example if below the 80% (can't increase str anymore) you gained points to your Reaction or Time unit stats. As it is i'm just loading my guys down with random stuff they won't even use because it is both the only way to train their Strength and it's mechanically disadvantageous not to.