It all depends in where you have to look to confirm your flap setting. The flap indicator in the SH allows the pilot to confirm the flap setting and change it effectively on take-off roll without taking your eyes off the tow plane. In a thermal with other gliders I never have to look down to confirm what setting I am in. In the SH "a" models it is harder to see the flap handle location so the position indicator is even more helpful.