I watched this video again and tried to take it a little further with the flying grayson cross up damage wise. Instead of doing the combo ending in sweep which does 32% do the normal bnb 1f1, mb ground spark b3, ji2, 3, 1f2 does 37% following with flying grayson which crosses up for extra 13% coming to 50%. like you said, no reason to not do this.