I said concavity when I meant convexity, which doesn't sound quite as right out loud while it means the right thing. it brings the tension/compression strengths closer to equilibrium, which is a big part of why osage orange is such a stable, reliable wood and BL is more likely to fail with use sooner.
My method for tillering is to get as much of the bend and weight figured out as possible before even stringing the thing. I count the number of corrections and re-stringings to challenge myself, and thus far have a high score of three with a piece of vine maple I should really get around to photographing. I don't know if it's at all necessary, but I've had good results using this method.
