The 440 series do contain more chromium than ATS-34, which would help with the corrosion problem, if one exists in your type of outdoor environment. I've used, and like, 440C; never used 440A or 440B. Any of them are easier to sharpen than ATS, but then ATS holds it's edge longer; all this assuming proper heat treat/temper/cryogenic cooling for whichever steel. While I like 440C, I've pretty much used ATS-34/154CM for a lot of years now. Corrosion has never been much of a problem here, and I like doing several deer before a re-edging is necessary. With the proper sharpening tools, any steel is easy to do.
