I'd like to know if these ATA specs are int their manuals. I just got off their website and there is nothing mentioned about arrow/speed requirements, etc. It may be in one of their manuals, but that costs $30 for non-ATA members. The last I ever heard of ATA requirements was many years ago and it was indeed called AMO at the time. And it was as stated above at 9 gr/lb of draw weight; 60#, 30" draw, and 540 gr. arrow. Bow manufacturers back then listed both AMO and IBO speeds. For isntance a bow might have an AMO speed of 245 fps and an IBO speed of 305 fps. Has the ATA adopted a new policy?
Just to be clear on this neither of these (ATA or IBO) are within the realm of realism. For one thing very few people shoot or should be shooting a 30" draw and the majority can't even draw a 70 lb. bow. And the specs allow for some variances. There should be no variance whatsoever. 30" is 30", not 30 3/4". 70# is 70#, not 73#.
The old AMO specs are not all that accurate either, any more. I don't know of anybody that shoots a 540 gr arrow, especially at 60#.
Personally, I think a nice medium would be to rate bows at 28", somewhere in the middle of what most people shoot. And it wouldn't do any harm to check the bows at both 60# and 70# and publish both numbers. Arrow weight? How about going back to 6 gr/lb for an average.