I have three ASH colts/stallions and they are wonderful horses. I also have two Quarter Horse stallions (including Days of Gold, thought to be the highest awarded cremello or perlino stallion in the world with 12 national titles including two from our Quarter Horse national championships). I adore both breeds and many of the top selling Australian Stock Horses have a high percentage of Quarter Horse in the background.
We used to have about 100 Thoroughbreds on our properties in the outback - about 36,000 acres with 10,000 sheep and 500 cattle. The Thoroughbreds were used for everything from mustering and campdrafting and polocrosse to showing and dressage - and racing, of course. When the Australian Stock Horse society started, Thoroughbreds formed the basis of the breeding, along with Quarter Horses, Arabians and 'unknown breeding' of good stock horse type. The result is a great performance horse that is extremely athletic and versatile.
One of my Stud Book Stock Horse stallions, the 3yo cremello Tintaras Chandra, is over 90% Thoroughbred breeding and many Stock Horse people don't like the obvious Thoroughbred type these days - though he is very popular with those who DO appreciate the fact that the Australian Thoroughbred is a magnificent performance horse. Our Stud Book Stock Horse colt, the Silver Dapple yearling Ahrem Time Out, is the more 'classic Stock Horse' breeding, and is more of a campdraft/cattle worker type - not as muscular as a Quarter Horse but the type that will work all day, every day, comfortably and reliably for twenty years and more. We also have a 3yo 2nd cross Stock Horse stallion that is a Champagne - there are only two champagne stallions in Australia over 10 hands, the other being a very nice imported U.S. Champagne Quarter Horse, and our boy is a lovely athletic, campdraft type.
I do hope that if U.S. breeders take up the ASH that they keep the horse true to type - a great, athletic horse that can muster in rough country all day long, do eventing to Olympic level, rein, work cattle, go to shows and win hack classes. A horse with GREAT legs and no obvious conformation faults. It is truly a great breed and it would be wonderful if US horse people learned to appreciate this breed of horse.