That is some flight test!
I flew one about two years ago. I had flown all the similar group A and D machines I could find. The Sting came top! According to my notes the perspective importers were going for group A with a MTOW of 550kg. I abandoned my interest as further investigation lead me to believe it was unlikely to get PFA approval, which turned out to be the case. I ended up with an MCR01 Club, MTOW 490kg, which was the closest I could find. Did you do a flight test on one of those?
Rod1