I am trying to go fast against other kiteres, the windsurf example is just to incite more tips.
I did try to use the wake of the windsurfer, and what a big wake, it work for a while but normally he would point more upwind leaving me out, then glide back to the course.
But again the race is versus a kitesurf.
I use a waist harness, I see the races with seat, and I guess is for comfort more the speed? ?