Hook grip, if one can get used to it, feels better for some people and is safer on the biceps. It's mainly just a comfort thing.
The pain is unreal. Especially if you don’t have long(ish) fingers.
Was wondering whether the double overhand grip allows the lifter to engage his trapezius muscles more effectively ,allowing him to "jerk" the bar at the start of the movement and increase the vertical acceleration off the floor.
The sumo deadlift,after all, is a more straight up and down vertical pulling movement than the conventional deadlift.