I remember posting this same question some years ago on the old PA board. Since day one, I've built my bows as they stand in the tree. And of all the stave bows that have broken, and there have been many, have done so on the upper limb. Only bow with a broken bottom limb was a billeted bow. That's the number one reason I prefer billeted bows built from the trunk of the tree.
Seems like the masters of old knew about uneven working properties and thus many of them compensated by using matching sister billets for there bows. More work, but greater rewards..........Art