What you could do though, is have stormtroopers who wear virtually the same amour, but have differences depending what weapons they 'specialise' in. Eg, standard troopers with e-11's would wear normal armour, troopers using heavy weapons like rocket launchers could have a large backpack on, like the sandtrooper has, and maybe some ammo belts around their torso, snipers could have ammo packs on the front of their ammo and maybe legs too, etc. It would help add more variety to troopers, but still keep them pretty similar.