It's funny when people say
this steel is sharper than
that steel. Obviously it comes down to geometry, except perhaps with S90V I've read that it's just impossible to put a hair whittling edge on it.
*edit* I stand corrected! Vasilli finally achieved a hair whittling edge on s90v
http://www.bladeforums.com/forums/showpost.php?p=6279713&postcount=1 It seemed odd that he couldnt until now, because he always said the carbides themselves could be sharpened/polished with diamond paste.
A lot of times these discussions come down to "heat treatment is more important than steel selection" but how many makers (that people actually buy from

) don't do a good HT? In my experience its a non issue, I dont think I've ever bought a knife with poorly tempered steel, except maybe a cheap steak knife at the dollar store. I just think it's kind of a moot point seeing as any maker with a reputation or repeat customers didnt get that by being incompetent at heat treating their wares.
Siguy makes a good point, with whittling wood it's a matter of edge stability. I've seen some microscopic pictures of D2 and 440C, they both have very large carbides (anyone know how many microns wide a razor edge is? just curious) and sometimes distributed in bands/strips, I imagine if one of these bands of carbides ran parallel to the edge it would make it much more fragile being that there's very little steel in between them. Though I suspect this isnt so much an issue with steels that have very fine and evenly distributed carbides, such as powdered steels and Sandvik steels such as 12c27.
Don't get me wrong guys, I have nothing against designer steels, and their "pros" really shine though in certain applications, but in my opinion due to the nature of bushcraft, the type of edge you want to maintain, the way our primary medium affects the edge in cutting, and of course maintenance that the Pros are out weighed by the Cons.
That being said I still use my Kosters in 3V a lot, I just dread having to fix the edge if I ding it up. Even on diamond stones it's tedious, took forever just to polish out the original coarse grind lines, and those are a lot shallower than a chip or dent typically is.