I had a Speed2 19 and would start crapping my pants over 15 knots. I know I got more pies than you too
The S2 19 and the S3 21 don't have the bottom end or upwind pointability of the X-19... by just a tiny bit. The S3 21 has more range and the S3 15 is a lot more fun.
If I were you, I wouldn't bother. Bottom end is what the X-19 is about IMO... S3 15 is about surviving the lulls and boosting like a nutter in the gusts.