A shorter brace height means the arrow has to spend a longer time on the string, thereby increasing the risk of the shooter torquing or otherwise interferring with the shot. Since it spends a longer time on the string, it also gets a longer power stroke giving more speed. So forgiveness would be less on a lower brace height bow, but I believe it has nothing to do with accuracy. Put both in a hooter-shooter and you probably will not see a difference...it is the human factor which comes into play. I think it is generally accepted that brace height plays a much larger role than ATA. HuntersFriend.com assigns brace height a factor of 7.8 vs 1.5 for ATA intheir computations for forgiveness.
From their site:
<BLOCKQUOTE id=quote<font size=1 face='Verdana, Arial, Helvetica' id=quote>quote:<hr height=1 noshade id=quote>Brace height is the biggest consideration - followed by axle-to-axle length - and finally IBO speed (minor consideration). The math is fairly simple Forgiveness= (1.5a + 7.8b) - (s/9) where a=Axle Length, b=Brace Height, and s=IBO Speed. Larger brace heights, longer axle-to-axle lengths, and moderate IBO speed bows score higher.
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Personally, I just went from a 38 1/2&quot; ATA 8&quot; brace bow to a 30 1/2&quot; 6 3/4&quot; brace height bow (Martin Altitude) and have not seen my shooting deteriorate because of it. I'm not sure why, but I think it has to do with a great riser design on the Altitude.