Unless I missed something, the original post ignores the down situation. On fourth and and goal from the 1, being in shotgun is different than first and 1. The main issue I have with being in shot gun on first, second or third down and 1, is that the result can't be simplified to "scored/Didn't scored". Big difference if you don't score and have a hold on first down, so that it is now first and 11, or the QB is sacked 7 yards deep, or a running back is tackled 5 yards behind the line of scrimmage on a screen, or if the you don't score but advance the ball to the 1/2 yard line on a QB sneak.