Hawk-eye can probably cut through kuma's body with low difficulty if he attacked him with full power. Kuma is definitely faster than Hawk-eye. The Kuma in the war showed this while he was fighting Ivankov. He went right past them in a blink of an eye and before, it showed luffy using gear 2 and evading mihawk and he looked surprised and looked as though he didn't know where luffy went. So, in terms of speed, Kuma is faster, imo and it's a one touch win for kuma if he manages to touch mihawk. Only think I am wondering is.. whether or not the pads on kuma's hands are strong enough to withstand the world's strongest's swordsman's slash? This, I think, is what we need to know in order to compare them and see who is stronger.
Peace