I was just on the Benchmade custom builder, thinking about a custom bugout. Along with the stock S30V blade, they list 20CV and M4 steel as options. I have a stock bugout with the S30V blade, been totally happy with it, but I figured if I'm going to spend the money on a custom, might as well upgrade the blade also. What would be the better of the 2 upgraded steels? More concerned with edge retention and ease of sharpening than corrosion resistance. Are they both about equal, or does one really stand out from the other. It'll see regular daily duty, opening letters, packages, breaking down cardboard, maybe a little kitchen duty, the occasional nylon zip tie, stripping wire, etc.