It seems the RS D2 has most of the Serenity's light wind speed with most of the Phantoms medium wind speed. But now kite course racers are using 'mini windsurfer' style boards (but with 3 fins), I doubt they can be touched by anything , except possibly a Hydro Moth (blade rider). Partly this is because the wind at kite height is stronger than measured at the surface. At the recent Olympic trials they were reported to outperform all the multihulls & skiffs present. However I doubt they would be suitable in inland conditions i.e. with lulls.