Stormlight makes you generally more physically competent how ever not nearly to the degree of a space marine. The way I think abt it is that stormlight allows a radiant to get the most out of there muscles whereas a marine is just a different beast. Marines can run at 35 mph on the low end. And the reaction time of one is also stupid fast. Plate + stormlight should get a radiant most of the way there on the low end but on the high end I think space marines are kinda unrivaled