Just to say it again - yes the claim that cats were banned is completely and utterly wrong. It's a stubborn myth that some people hate to see disproven, apparently because they love to feel that multis were discriminated against by some big bad establishment. However the fact, as clearly demonstrated by reports of the day in the NY Times, Brooklyn Daily Eagle and other newspapers, is that after Amaryllis' first race cats were treated like every other type in NY, or a bit more favourably in some ways.
Amaryllis was DSQ'd from that first race and given a special prize. First prize then went to Jacob Schmidt (aka Jack Smith), an immigrant saloon keeper, hat maker and sandbagger sailor - not exactly a member of the "establishment" and probably less 'establishment' than Nat was. And the NY "establishment" of the era was arguably the most progressive and inventive bunch of sailors ever seen in the world. In the space of a few decades they basically did things like introduce the Herreshoff (and Fearon) cats, invented ocean racing, introduced the "skimming dish" hull, introduced the first rating rule, took part in the first international races in medium size, small and big yachts, the first international races in small centreboarders, the first Bermudan rig in major racing, the racing scow, etc etc etc. Just like many of their British contemporaries, many of them were among the leading inventors and industrialists of their day. To class them as the sort of people who would ban cats is completely wrong.
Cats were then raced for several years in New York in a separate class, just as almost all other types were raced in separate classed divided by rig, type and length. Cats were owned by powerful people like the commodore of the New Jersey YC and the rear commodore of the Boston YC. The founder of the New York YC and the America syndicate, John C Stevens, had owned the cat Double Trouble decades before as well. A cat was also allowed to race with the New York YC itself, but it performed poorly. The "open' cats didn't race with the monos but that was simply because in those days each type normally raced by itself - sloops raced sloops, catboats raced catboats, schooners raced schooners - there were almost no "all in" events and perhaps none at all.
Cats also raced with the New Orleans YC and places like Salt Lake City. A few years later the first cat in Sydney, Flying Fish, was also owned by a club commodore, in the form of Mark Foy, famous for fostering the 18 Foot Skiffs. Flying Fish regularly raced with the Sydney Flying Squadron, where (despite myths about her speed) she was rated about 2 minutes slower than the 22 Foot "skiffs" and the Raters.
Yes, LF Herreshoff wrote one sentence that said that cats were banned and many people have since relied on that as the only evidence that the ban occurred - however the indisputable fact is that there was no such ban, and this is completely and utterly proven without doubt by the records of the time which are now available through internet archives. The on-line archives of the Mystic Seaport Museum also show without the slightest doubt that LFH knew that cats were not banned, because his own letters on the archives include passages about their racing and saying that Nat was happy with the way the cats were treated. Why he made that mistake is a mystery, but the fact is that he was wrong - as his own words show.
The Mystic Seaport letters also show that LFH wrote that he thought that cats were slower overall than monos of the same length, and that Nat wrote that the days of the multihull were over once outboards arrived and that cats should not have cabins. So no one can really claim that the Herreshoffs were always infallible - they got it wrong at times like everyone else.
It's understandable that the myth was believed in the days when people couldn't check up on the facts on the internet, but this is 2016 and there's no excuse for believing it now. All people have to do is to go to something like the Brooklyn Daily Eagle archives, type in catamaran, and read the facts in the papers of the day.
As a cat owner I really wish this myth could be killed once and for all, because it's given some multi sailors a chip on the shoulder that has probably done more to hold back the cause of multihull sailing than any so-called discrimination by monohullers ever did.