There is only so much that can be conveyed in still images. In this most recent rocker, I was striving to create motion, in both the lines of the chair, but also in the actual wood. Folks who have tried it out have all commented on the gentle "give" of the back. I have wanted to build a chair that had the flex of a combback, but without the arm passing across the back.
The ability to match the curve of the back is only part of the challenge. If the chair works only in a single position, the sitter will soon become fatigued and need to shift. I found that the added dimension of flexibility can help create comfort while the sitter takes on a number of positions, because the weight distribution of the sitter actually reforms the shape of the chair. It may sound obvious, cushioned chairs do it all the time (often with too much "give"), but we're talking about a wooden chair here, and by using split wood, shaved along the fiberline, I think that the challenge of making a "hard" chair "soft" is met.