I'm sure ol Adcock did extensive testing I think with the convex back he was trying to componsate for poison efect in the bow to and I read he had problems with limb edges splitting it could have been the material quality of the times , but my thinking with the minor concave that I end with after narrowing ,poison effect is moot with glass or glass/carbon at least that's how it's working out on my current shooter with the limbs at 1 1/4 " I'm basing this design loosely on composite horn bow limbs where they have convex shaped belles & Im putting a double chamfer on both back & belly lightening the outer edges for mass reduction I have found my current bow to be exstreamly stabil , I'm not basing the design ACS or Adocks design just used it for a analogy of a curved limb , I'm guessing the concave back is putting more tension stresses on the the outer back edges and more compression stresses on the center of the belly but so far the design is working out , maybe the bow will blow up after 1000 arrows I don't know just exspermenting ! Sorry for the winded post just trying to explain the difference !