I purchased a 14m Diablo and have flown it about 6 times. This is a great C kite, and my first OR kite. Ive owned Naish, Sling, Best, Wipika, and Windwing. The range is great. I can stay upwind in around 12 knots (easily match or better another rider on a 16m Rhino) on a twintip. In fact everyone else was on the beach while I was riding in light winds. In squalls with wind up to 25 knots it depowered fine by pulling the trim strap, handles gusts with ease. It doesn't have the magnitude of quick depower by pushing the bar away as a flat kite. The bar pressure is less than my old Best 12m Nemesis, and about the same as a 12m Rap 1. I ride it with a stopper ball nevertheless, and it feels very easy riding and comfortable this way. Unlike the '05 Rap 12 (which doesn't fly forward), this kite darts forward in the window but without yanking you, when you stomp on the board (something I prefer.) Yes the upwind seems to be very good, but I've never had trouble making any kite go upwind well
The kite seems to have a tightly shaped canopy with no wrinkles in flight. I imagine the scalloped TE shape helps to tension the TE in flight which might help the whole canopy. The struts are super thin which speeds up set up, and have "dump sticks" built into the velco valve covers which make deflating the narrow struts and LE very fast indeed.
The kite turns on axis within its own size of air space. Downloops are instant with a good jerk on the bar. 50 cm I use bar is plenty. The turning speed is impressive, at least twice as fast as a 2004 14m Best Nemesis, and as fast or more than the 12m Windwing Rapture. It is stable when underway, but don't take your eyes away on land since small bar movements send this kite.
Jumping seemed standard to me, although I'm not a superb jumper.
I had to relaunch once in junky light wind (on the outside of a reef in Hawaii !!) It took me a while, but she got in position and went up. Haven't tried in proper wind. I think the LE (and struts) needs roughly 6 to 6.5 psi to hold proper shape and doesn't need more that that, based on trying with my gauge.
Overall I'm very happy with easy riding feel and performance of the kite. With this kite and a 9m flat style, I now have a 2 kite quiver. And also use a skim board and surf board for ultralight wind.