Rolf,
I've had an TheMightyHobie18 Magnum, and still have a SC20 with symmetrical boards, and Flight Risk just points substantially higher. If I pick out a point on shore as I'm heading in, and attempt to maintain a straight course, I can see the boat working to windward. Have done windward leeward with J boats and 35' racer/cruisers and I can either point as high as they at their upwind speed, or bear off 10 degrees and beat them handily to the windward mark, in less that 10 kts of wind. My other boats (admittedly in my hands) haven't performed that well. The difference seems very noticable to me, though I doubt I'm as sensitive as you experienced racers. So I'm puzzled that they aren't tried more commonly. It may be that the required switching of the boards with each tack/jibe is too much hassle or time, for racing. Pretty fabulous for long tacks/reaches though. Having the "wrong" board down works well pulling the boat to leeward on downwind runs too.

Dave