Ya must've missed my last sentence George...judging by tension,compression,and elastic properties alone its number one,and that's what allows it to be smaller than other bows. Make those others the same dimension and try to get the same bend with them and see what happens. Are they equal now?
We are past the point that design can make a lot of other woods equal to osage.
Even if you adjust your dimensions to make it equal in set loss and cast, I believe the majority of the time osage can take more abuses such as overdraw,being dinged,etc...make ten bows,all 50" long,5 of ash and 5 of osage and design both correct. Tiller all to 65@25". Now overdraw all those bows a couple inches+ repeatedly shooting them and see what happens. The osage will hold up better because it is stronger in tension,compression,and a higher elastic modulus.