TomD
"Steve Knight's O1 does (it's pretty much even with A2, but leaves a better surface), but I have had success making similar quality irons with Starrett and Precision Presto O1 and leaving them around 62 hardness."

O1 is dead cheap, and it's main quality as a gauge block steel is that it holds it's dimension well. I have cracked a few pieces doing heat treats in stupid conditions like out of doors, mid winter, but I don't normally have any problems making pro quality tools out if it. So I am a little at a loss as to why A2 would be so much better. The HT stability is a factor, but I don't see how large given that O1 is a favourite among beginners all over the place.

I think LN is probably right about nobody wearing out their tools, I know I only have a few that look like someone serious owned them. The reality in the modern world for the most part is that heavy users change their gear so often they never wear it out by hand. Someone with a heavy hand at the grinder could, though.

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