As Shoki has already said, kudos (and thanks) to the devotion, detail, and effort you put into your analysis and response.

I've actually been thinking on this one myself ever since seeing the original discussion in the other thread (the mech. engineer in me always looks for a way to come out since I've changed professions and it's no longer my career) - and I concur.

I'll defer to brevity in my response since you've already covered my views in great detail. So, in short, I agree - a purely rotational will cause the blade edge to effectively meet each hair in such a manner as to impart almost all of the energy/force in a head-on direction - thus attacking the hair in a chopping motion. Any other directional occurrances - e.g. deflection/bending of the hair, slope of the blade in relation to the plane of the skin, etc. - will be immensely insignificant in relation to the main rotational force...

And, as any chef, sword master, butcher, carpenter, box cutter user will attest to, a blade always works best and most efficiently when its force is applied in two directions - i.e. slicing and chopping at the same time such as when a chef's knife is pushed or pulled while also moving down through the tomato.