The SS swingarn is only ~ 1.5 - 2 inches longer (can't remember and have not measured them) than the S. Some of the wheelbase is picked up in the frame of the SS as well.
Here is an SS swingarm.
Note how the shock perch is positioned further back than the regular S swingarm. Also, the SS does not have the recess on top of the left leg for the brake caliper like the regular S.