i think i know what you mean and i don't think anyone here can answer that.
first, dan's never done it to my knowledge.
second, swamp rat has done it. you're assuming that if the through hardened knife was 57rc, the differentially temeperd knife would be 59 on the edge and 55 on the spine. that makes sense but honestly, i don't think even Busse, masters of the heat treat, have that much control over the hardening. the spine will be softer than the edge, which may be 1rc or 2 harder than the through hardened sr101 knives but i don't think they'd do that with sr77.
still, all just a guess. i don't think through hardened sr101 needs to be 'less hardened' to still be worth of its family.
I was also thinking that the through hardened mihgt be 57 Rc and the differentially tempered blade might be 59 Rc on the edge and 57 Rc on the spine. So in making the entire knife 57 Rc you are gaining tensile strength but losing some edge retention whereas you get the best of bost worlds with the differential treat. I think a better sacrifice for a small blade would be to bump it up to the 59 Rc where it has its greatest edge retention and sacrifice some tensile strength.
