Hi Joel, well, try to use parts off a modern AW on a 1930s one. You´ll have some problems. Besides S/A meant to replace the A-series with the S-series in the fifties, but as the SW proved to be unreliable, it was discontinued, SC and SM variants were not introduced and the A came back.
So, yes, the name has been around for a long time indeed, but to my mind the real whopper at longevity must have been the German Fichtel und Sachs Torpedo single speed coaster hub. First models were introduced in 1903 and 1905, and the one that was made until 1993 at least appeared in 1908. And excepting two, all parts stayed interchangeable.
You might think, well, a coaster hub, and what about CR rules. Those Torpedoes were used for racing purposes in Germany until the fifties, sometimes admittedly in a lighter version (Renntorpedo, "racing T."), but very often just in the standard version.
Some derivatives (again with all or nearly all parts interchangeable) are still being made all over the world, China, Russia and the Czech Republic being just some examples. Both Sturmey and Perry made thinly disguised copies for export markets, and one of the most beautifully finished hubs in all of my cellar must be a Polish version from the sixties. Yes, there are some Campag/F.B., Airlite and Blumfield equipped bikes in that cellar, too.
Regards, Toni "Nie ma problemu" Theilmeier, Belm, Germany.