A lot of work has gone into bringing some level of kit standardization for fighting units. Some better than others.
But based upon the original title of this post the question to ask is load out.
There is no right answer for load out, yet the answer is very simple. It all depends on the parameters of the task.
Considerations from logistics, location, weather, # of days, task, enemy size, type of battle etc etc., all go towards the calculus of what the load ought to be.
Physical strength is very important. Ability to carry weight it very important. Not just from a load perspective but from other considerations as well.
The single biggest variable is ammo. When on patrols away from logistics in rugged country, ammo is the biggest consideration. Depending on the type/ferocity of engagement you'll be surprised how fast you cycle through ammo. The worst thing for a soldier is running out. Without lines to replenish it is important to carry as much as physically possible. Then nature of terrain and weather has a significant impact of the load. Ballistic gear is not always necessary. If the task is hit and run - then being light is the way. If task is to engage and destroy then load changes. Terrain and weather adds a level of variability. If terrain is flat with little cover then there is a different approach to locations with cover.
But there is one variable that is a constant and that is the physical strength and endurance of a soldier. Just jacking up and bulking up is not good. There needs to be a balance of endurance and strength. Here too PA has brought in especially during Kyani's time greater emphasis on endurance and fitness. Still a long way to go and hopefully the Army will keep sticking to and enhancing these programs. Over time our soldier will be sharper and more effective IA.