Update from the Northwest. We are predominantly Hobie-only (will be next year per the mandate). We only had 2 or 3 non-Hobies: a couple Inter 20's and a Prindle 19. We saw a slight dip in attendance at regattas this year as several sailors (incl. Ken & Eric Marshack) bought A-Cats and developed their own circuit.
We are seeing incredible growth in the Hobies, particularly the Hobie 16. For the past 3 years we have been teaching Hobie 101 and 102 classes to standing-room only crowds! Nearly everyone who sails a beach cat today started out on a H-16 at one point or another. Our Hobie 16 fleet in the Northwest hasn't been this big in 15 years!! We are already seeing the H-17 and H-18 fleets grow, too, as some people get bored on their 16. I expect the A-cat fleet will see growth from this well. It is just a matter of time.
For us here in the Northwest, the key has been educating and providing opportunities for the new sailor. People from all walks of life are (re-)discovering the thrill of catamaran sailing.