Heres somethin that will really blow your skirt up.... A stave, say naturally reflexed 3" on one end and naturally deflexed on the other....you put it on your form and reflex with any heat source to make the limbs even out...now consider that the limb that was deflexed, is now reflexed.... That limb is already under more stress(or atleast structually inferior) to the naturally reflexed limb... The belly wood has been stretched and the back has been compressed. The naturally reflexed limb is still in close to its natural state...this makes my head hurt abit, lol.... I guess if i had a point to make it would be that once we have changed the natural shape of the wood were assuming alot more than actually knowing what a good tiller looks like and like what has been said already, depends alot on "feel".... Brian