I bought a second hand Spirit 15m.
Juste tested it today , 6 to 12 k knots on 24 m lines and 1200 cm2 foil.
Kite is easy to launch, powerful and a real freerace kite : rapid but still tolerant. Really beautiful in the sky.
Compared to lower ratio like Pulsion or FRS, you need to keep an eye on it at Zenith if wind is not very laminar.
Hang Time is excellent, kite is forgiving but gives a lot of reward.
I think my low end limit will be 6-7 knots if i want to keep a bit of tolerance before collapse. Jump in 7 knots were great , both long and easy to redirect before landing, a lot of hangtime.
Under 7, i prefer the pulsion for its hanging in the air, stability ,and recovery in case of rider mistake at the extrem wind windows. I feel more confident to still try new unmastered tricks in 6 knots with pulsion. For tricks masterized, Spirit is more rewarding.
Nice kite, really, and already looking forward for the next session, maybe with shorter 20 meters lines