Toomanyknots, I ont understand what you mean by doing it naturally? I have 2 natural reflex deflex grown staves of mulberry that I will be working soon ( I hope ). I would assume you dont mean naturally grown that way so other than steaming or gluing up, how do you naturally deflex a bow?
As for string tension, I bet you can get very high tension with a r/d design. This will depend of course on draw weight. I believe folk intentionally r/d a bow to allow a longer draw and lower limb stress per that draw length. That can be very usefull with a short stave that is too short to get your normal draw length/ weight otherwise. Correct me please if I am wrong, but that is my understanding of the designs purpose.