Light here.
Idea of fast movement + close fight weapons like blades, or pistols is sweat.
Also sniper + fast place changing.
Maybe I missed it, but aside from health and speed, are there really any other reasons for going small, medium, or large? Such as puzzles, obstacles, etc that one body type does better, or is able to get through. EX: Small hatch that a small body can easily get through; medium is gonna be scraping skin and armor, and large....well, your not getting through, so you guarding the entry big-boy.