Agree strongly with Alexrider/pumpy. Speed 4 8 dlx is my favorite and most often used kite with the foilboard. I guess it is very similar to the hyperlink, just ahead of its time.
Sonic 2 is a great kite, but harder to relaunch. And I have a ton of experience in relaunching the S4 8 and 10 dlx while learning to foil a couple of years ago. Sonic 2 needs a lot of preinflation, then a careful launch to get the wing tips filled. But then it is very solid. No collapsing of the tips during turns, or ever, really. Also it is faster turning on a shorter bar. I only have the 15, but it's great.