Yeah the SX seems to be very stable. I've been flying in wind a lot lately, 20 gusting to 30 kinds of winds and my quad, Avroto 2814-11's and 12" props has been very smooth and predictable. I'd be very hesitant to fly in that sort of wind with any DJI but I don't think twice about it now. I hope that's a good thing.
Also the thing that I like about the SX in GPS mode is that when you switch to GPS it seems to log its location and then calculate its position relative to that point so it doesn't feel like you actually switched modes, its exactly like flying in attitude mode and then when you center the sticks to hover it resets the point. Thats feels very different top the way DJI does it. It would also explain why you can do a RTH and it works very well even without GPS lock and might explain why DJI has so many problems with uncontrolled flight.
Since Hoverfly seems to have scaled back I'm cautiously optimistic about the future of the SX.