M-2 will take a fine edge like 1095 but hold it longer. That is the whole point of tool steel, or high-speed steel in the case of M-2, to add alloys to make the steel more shock resistant and more wear resistant.
We discussed ATS-34 vs. M-2 to exhaustion a couple of years ago when Benchmade first came out with the M-2 AFCKs. I guess posts that old would be pretty hard to dredge up out of the archives at
www.benchmade.com, or rec.knives, but it might be worth a try.
The key differences between M-2 and ATS-34 are that M-2 has Tungsten, more Vanadium, and less Chromium. The Vanadium and Tungsten form very hard carbides, thus the higher wear resistance. The lower amount of Chromium means M-2 is not stainless, and it tends to have a nice fine grain structure, meaning it takes a nice fine edge.
M-2 is capable of hardening into the 63-65 RcH range which results in very high wear resistance, but also has given the steel somewhat of a reputation in the cutlery community of being brittle. If you draw it back to around 60-61, though, it is darn tough, and still holds an edge better than stainless steels and probably still better than simple steels like 1095. M-2 is not stainless, but does contain some Chromium which makes it somewhat less prone to rust than simple steels.
In the particular case of Benchmade, the M-2 blades take a finer edge, are much tougher, and hold an edge at least as well as the ATS-34 blades.
Hope this was useful.
Harv