While I am not really competent to tend to any differences between Fred Astaire studios and other teaching studios, I do know that Fred Astaire is a member organization of the National Dance Council and participates in the syllabus committee. In the past several years, the Fred Astaire dance syllabuses have been completely revised and rewritten, probably bringing them into line with the NDC standards.
I have been taking lessons at FADS for over 5 years and I know that there are many, many students and teachers that participate in competitions outside of the FADS system including Black Pool. In fact one of the pro couples from Florida won last years cabaret division at Black Pool and were featured on "So You Think You Can Dance" closing episode. Our "traveling" coaches feature teachers that are former world champions. For example, my smooth coach is Michael Meade, 5 times consecutive world champion in smooth.
I think that if you examine the teaching methods and syllabuses used, you will find only very slight, if any, differences between FADS and the NDC standards.