The Gaastra 16.5, I ride it today with some other kites in the water, wind 10-16 knots, better then: ARX 15.5m', X2 16m' and AB 11.8m' (faster go better up wind and jumps great).
The Gaastra jumps much better and easy to handle and jump, built as good.
the 14.5m' 12-14 to 28-30 knots. the 16.5m' 9-12 to 22-25 knots.
The Gaastra is a pro kite, very good one.