General,
Let's assume that Mr. Mayo knows a little tidbit or two about blade steels
(click on that little link in his sig and get a bowl to catch the drool)
mjoury,
The only advantage M2 has (in my experience) is that it will roll rather than chip.
Whether this matters or not depends on what kind of use the knife is going to see.
My only M2 blade is a 710HS that is used in a very rough environment. I use a knife daily for a wide variety of jobs.
IMO, if you are cutting something that will chip out ATS-34/154CM, you probably shouldn't be cutting it with a knife, anyway.
I've chipped ATS-34 and ATS-55 (and, as of Friday, 420V) by banging the edge into steel or concrete while cutting other material-never from use. But accidents happen when you're working hard and fast+don't always have time to get the proper tool, which is why I normally carry the 710HS. It's alot easier to steel and strop out a rolled edge than it is to regrind a chipped one.
Aside from toughness, I like 154CM better, personally.
The statements that 154CM is more wear resistant, but that M2 holds an edge better are a direct contradiction
M2 has its uses, but it's not some "super steel" like so many people make out. It is great on a knife that's going to be
abused.
Note:my experiences and opinions are limited to a handful of knives, but some things, like trade-offs between steels, are pretty universal.
So...what do you normally use a knife for?