Area10 said..
The logical progression of this is that you only stand up when you are on a wave, and use a prone surfboard.
Patrice Guenolé, the Gong shaper, has been doing it since 2008, see:
www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/The-Paddlesurf/But interestingly, he only does it from time to time, it never became its main way of SUPing. Why? because it is a specialized practice, not something for everyday waves.
So I guess we only need now for contests to have rules/categories to mirror the different actual practices of people... Maybe with sensors to gather speed, acceleration, ride length, angle of turns to have some other judgement criteria than just go-for-one-big-turn-in-a-closeout, maybe as a parallel ranking?