Excellent analysis. Interesting that the flak vest and helmet factor into the equation, and the armor worn is typically given almost a pass in many Traveller variants. What this analysis tells us is that it is total load weight (as a percentage of body weight) that ultimately matters (at least until you get electromechanical/hydraulic power assists). That said, effective LBE (load bearing equipment, for those who haven't spent time with Uncle Sugar's merry band, or its equivalents) does increase the individual's ability to function despite a "reasonable" load (and bad/no LBE decreases it) because it helps distribute the weight. That said, you still feel the marked difference when you take it off !
In the world wars, many combatant nations had what was termed a March Load (pack, bedroll, extra ammo, spare clothing, etc. etc. kitchen sink), and troops would drop packs and leave them with the company first sergeant just before going into the attack. (And then we have the first day of the Battle of the Somme, as the counter-example.)