I know he hasn't surpassed Mihawk, but lets not downplay Zoro. He was fighting both King and Enma. Once he got Enma under control, it was a low diff.
he is basically oden
since that form still has some time adjustments and limits (like G4)
its hard to call zoro and king a low diff cause you know he has to take on his stronger/limiting form atm to do so.
its a mode suited for fighting much stronger people than king for sure i.e g4 luffy vs doffy was closer to a mid diff but luffy vs doffy overall is closer to an extreme one.