Mr. Dufour did a Cotes de Geneve demonstration for us when we visited him, and if I recall properly he used a spinning ebony wheel that was actually in the shape of a dome -- so the only the sharp edge of the spinning "dome" touched the metal as he moved the piece by hand.
This was a complete contrast to what we saw at VC, for instance, where a piece of abrasive paper is attached by vacuum to a spinning chuck and the spacing of the stripes and speed of the application of each stripe are controlled by machine. I guess you can call it hand finished, but in a very different and more mechanized way!
Philippe is not the only person who is using old school techniques for striping, of course, but I agree with you that his stripes are the most subtle I have seen.
Best,
Gary