Can I slightly hijack the thread and ask how close AUS6 is to AUS8. I think that's what my kershaw vapor is and you guys have described my impression of it exactly. Easily sharpened, scary sharp, won't keep it long.
AUS-6 used to turn up in a lot of Japanese-made folders back in the '90s or so, maybe earlier. I think I still have a couple of them. The memory I have of their edges reminds me a lot of 420HC (think: Buck or Case stainless). Generally, that means it takes a great edge with minimal fuss, and with simple tools. I've always respected most of the Japanese-produced knives, because they always seemed to get the most performance out of whatever steel they happened to use. Beautifully-slicing edge geometry, sometimes combined with some wicked toothy edge finishes. My first real bloody bite came from a very toothy AUS-6 blade that closed on my finger and left a lasting impression. That particular knife was a Parker-branded (maybe his 'Eagle Brand') knife made in Seki City, Japan, if my memory serves. I think I have one or two older Spydercos in AUS-6 as well.
The carbon content of AUS-6 is a little lower than AUS-8. In theory, that usually translates to a little less edge-holding capability, though with the knives I've seen, I'd say they're still quite decent.
BTW, I'm in agreement with most of the others here, re: AUS-8. Can take some very fine edges, and holds them reasonably well. More reputable makers can do a lot of good things with it (A.G. Russell Knives & SOG Knives come to mind).
David