I go back to an excellent article by maker Dan Farr in March 08 Blade magazine. In essence he argues that the steel choice varies by blade size:
"How much of a concern is toughness in knife design? If you are interested in making and/or using swords, it may be your No. 1 criterion when selecting the steel and the heat treat. The speed of the sword blade generates tremendous impact energy.
Conversely, the other end of the spectrum is a hunting knife with a 3-inch blade. You just cannot generate the blade speed and high impact needed with a short blade."
Farr says that therefore in a large knife, carbon steels are the best, but
"If you include folders, where toughness is not paramount, I own more stainless knives than carbon steel. I carry a folder made by R.J. Martin every day, and it has a blade of CPM S30V...Many times, exceptional toughness is not needed in the steel. On occasion, edge holding trumps impact resistance. If the knife is so tough that it cannot be broken by hand power it is tough enough."
And although he doesn't directly say it, he appears to imply that S30V has superior edge-holding to carbon steels. As far as I know this is true, because of the greater wear resistance provided by chromium and vanadium carbides. The reason carbon steel is so much easier to sharpen is due to less wear resistance, but this also translates to reduced edge-holding.