Flexbone pistol. You can motion and run just about everything you can out of splitback and its really easy to go wide and spread the defense. Even if you rarely do it the opposing coach must spend time coaching against it. Motion to trips, rocket toss, jet sweep, midline, veer, motion to I and all out of one formation gives lots of options. Of course there's a chance to get carried away with it too and do nothing well. Just my opinion.