I have in my shop 3 bows as identical as they can get, all red oak all silk backed. I have one that has 1" of set and one that has close to 3" set...but the one with 3"set has a better cast of the three, this goes against common theory. I have laid them side by side and shot them countless times and the one with the most set has the flattest trajectory.
But I have a white oak that has virtually no set, it is unbacked and one of the smoothest bows I have made.