The well designed SL sets are designed to have the entirely same setup for each club.
The traditional iron sets require that each club has its own unique setup procedure, especially in terms of ball location.
You mention that a 1/2" difference in where you grip the club makes an unnoticeable difference in your results.
However, the real reason why the SL technology is gaining interest is the stup at the other end of the club. With SL you have the same setup for each club, same ball positioning, same posture, same point of aim for the intended shot. The 1/2" difference may not make a big difference for you at the grip end of the club, but setup with the ball 1/2" forward in your stance and the difference is more noticeable.