David Weaver
Derek - I agree that the stuff finer than 1 micron can be felt.

A buddy (who bought the shapton 30k glasstone) and I took a few pieces of sample stock and planed them off of his 16k glasstone, my 15k pro stone and his 30k glasstone.

We then viewed the pieces in raking light and tried to figure out what we could see as a surface improvement and could see none.

But you're right about the HSS, it's a whole different league, and diamonds can make a bigger jump than anything. I have only gone from 10 micron to 0.5 micron, but I was able to make that jump just fine with loose diamonds.

I might be quicker to my grinder than most. Usually on something like a stanley 750, when the flats in total are the same area as the hollow or just a little bit more, I'll be back to the grinder. If I think i'm not getting what I want, with the final polish stone I'll lift the chisel just a degree or so for two strokes. That amount ensures a good edge, but doesn't make it hard for me to raise a wire edge the next time I sharpen without lifting off the reference flats.

It's all details, and none of them matter, I suppose, everyone has to find their own ways. Three years ago, I was hard into the powder metals, but I think I have new tool fatigue, and I probably will not ever venture into more exotic steels.

I did get some veritas 0.1 micron film to play with on razors. I'm jonesing to give that a shot, but haven't yet.

Anyway, I like the 5k for what it does on japanese irons. Most of those aren't nearly so tough even as A2, unless they are super super hard, so my reference could be off a little since I nearly never use the 5k on western tools.

I have used it some for flattening backs, though, and like the japanese tools, recall that it does a decent job of bringing up a polish, and its tendency to load (which it has) can be mitigated with technique.

I guess I haven't really found any stone in the 3-5k range that I think is the world. Fujibato's 6k house brand magnesia stone is maybe the closest, I guess wet stone to wet stone, it's similar in grit to the shapton 5k, and I'd include it in that range, but it feels like an expensive stone.