Ive seen most all production metals an I think M2 has the best edgeholding properties of any. What M2 doesnt have that makes it undesirible to spyderco is ANY corrosion resistance. M2 has no resistance at all, so unless you are classified to field strip the knife for cleaning, M2 blades must be teflon or likewise coated. Spyderco has never, to my knowledge, carried a teflon coated blade design and they dont appear to be interested in doing so. This keeps cost down and the knives probably look better overall. From what I hear from an armorer of mine, talonite is comparable to M2, but much more expensive and much harder to work with and sharpen in the field. For now, IMHO, M2 is the best high performance steel if you dont mind taking good care of your tools and 440V is a great choice for people who want workers to which they dont have to pay much attention. I think 440V is a VERY intelligent choice for spyderco, and I encourage them to pair it up with liner locks in their new models (and maybe upgrade the civilian too!).