Lest us not forget, Old Timers USA were 1095 carbon steel
Carbon steel is easier to heat treat, and many custom makers that use 1095, can and do heat treat Carbon Steels themselves, thus having quality control of the "whole" knife, including heat treat.
In later years, Shrade quality slipped, the heat treat was not the same, many felt this was the signal Shrade was having some serious problems, as were other USA mfgs.
Stainless heat treats different, and the Taylor made Sharpfingers are a stainless steel.
All the Old Timers are a stainless steel now.
In the old days, folks bought Old Timers for 1095 carbon and the Uncle Henry line, for the stainless blades.
So a person that makes knives, and uses 1060, 1075, 1095 Carbon steels, even 01 tool steel, can heat treat their knife.
Stainless they send out to be heat treated, Paul Bos being the most well known, though other folks are quality "heat treaters" as well.
Heat treat can make a bull chip work, but you gotta know how to heat treat a bull chip.
New Sharpfingers "feel" like 420J2 , to me. I only freehand sharpen...so they feel like this to me.
J2 I understand was never meant to be used for knives per se' but it is now, by quite a few folks such as Buck, Kershaw and others.
Buck, can control the heat treat, and it my understanding set this up, to meet standards, Bos inspects on the ferrin' jobbies.
Imperial, if memory serves me right, Imperial used 1075 in their knives, including fixed.
Well phooey! 1060, 1075, and 1095 is what was and is still used for bayonets, machetes, and other uses, hard uses.
Opinels are 1075, and they too are hard used knives.
So, what we have is, heat treat on old Old Timers, Imperials, and Opinels, that are carbon steels that are proven.
Heat treats are "easier" for lack of better way of stating it, where stainless "has" to be done more "so-so" for that particular batch of stainless.
New Sharpfinger is a "stainless steel" of who-knows-what quality heat treat.
Honestly, one is better off buying a Opinel for $10 or less, than a new Sharpfinger which sells for more now.
The bottom line: What are you getting for monies spent?
You ain't getting spit with a new Sharpfinger, IMO.