I have 440C in several knives (4 versions of Benchmade's Griptilians, and one Spyderco Meerkat). I have been using my first Griptilian (550) for a year now, and have nothing but good things to say about it. I am certain that like any steel, heat treat and edge grind have everything to do with the quality. The 440C of my Benchmades (I haven't used the Meerkat a whole lot) is, IMO, pretty close to an ideal stainless blade steel. It takes a scary edge, holds it pretty well for all-around uses, is very easy to resharpen on my Sharpmaker, and so far has been very rust-resistant and not brittle at all.
I like edge-holding, but I do NOT need a blade steel that holds an edge almost forever, then is a bear to resharpen when it becomes necessary. The only knife I have in 440V is my Military, which I love, but I do not use it as much because of the resharpening difficulty.
Perhaps the 440C knives you have used had bad heat treat, or were mismarked 440C. As for the older Buck 110, the main reason it was hard to resharpen is because it had a convex, "apple-seed" edge grind. And I do not think Buck ever used 440C, at least on the 110, I think it was 425, and now it is 420HC.
I know for a fact just because a blade is marked a certain steel, does not mean it is up to the potential of that steel's name. The 440C on art knives (BTW, a lot of art knives are made of 420J2) is almost certainly not the same heat treat as on the Benchmades.
I've had nothing but good luck with the 440C. I haven't had much problems with ATS/154CM either. I am anxious to try out something in VG-10.
Jim