As of January 2016 I decided to try something new and bought two KA Race sails. The Race is KA’s full on slalom sail. With the Koncept line being the speedsails the Race is a bit heavier with 4 cams and has a lot of power.
The processing of the sail seems to be good, the monofilm is relatively thick, making a durable sail. I especially like, that every camber is accessible via a zipper, making it really easy to pop the cambers onto the mast and derigging the sail. The rotation is good, but I experienced that lowest batten needs to be tuned just right as this batten has a lot of profile. All constant curve masts are compatible.
The sail starts planing rather early. In the smaller sizes some people prefer the KA Koncept over the Race sail as the Koncept opens up a litlle more in the gusts and therefore gives some more handling, the Race feels more powerful and keeps more speeds in the lulls. So when it comes to choosing it is really up to preference. I also use the Race for speedsurfing and did my PB on a 5,5m sail with 36,70 knots average.