if I was curious, i would build several,,and shoot for distance or through a chronograph,,
maybe the deflex allowed for a longer draw,, just guessing,, im sure for close range hunting or war, it worked great or they would not have done it,, maybe the deflex allowed for longer time being braced,,
test one where the deflex is bent in, and test one allowing it to take set and see what it does,,that was a good question,,if you were going to make one with sinew back,, then pre bending the shape would probably work,,,