I recently got a Case Sodbuster Jr with CV blade. I love it. I think it takes a very nice edge and is very easy to sharpen. Personally I feel it keeps it's edge fairly well. SAKs are the same really; they take a fine edge and while they don't hold it like some super steels out now, it's very easy to get a razor edge back on. In my opinion though, SAK INOX is easier to sharpen than CV, but CV can't be considered hard (I think its because CV is heat treated to a higher RC.)
I don't have a Queen D2, but I do have some experience with sharpening D2. If the edges are nice and sharp to begin with and bevel angle is low, then it's not that hard of a steel to sharpen PROVIDED you keep it at a razor sharpness constantly and don't let it get too dull. Unfortunetly from what I read, Queen has a problem with very dull, obtuse bevels that'll require rebeveling on the buyers part, not really something to look forward to unless you have something like extra coarse diamonds. On the plus side though, D2 will hold its edge longer than CV.