With regard to your question about old AMK vs new AMK, within my limited experience, I feel that the old ones had better fit and finish.
I have an old Quicksilver combo edge, which I bought in the mid-80s. Smooth opening, good lock-up using liner lock, very clean polishing, strong clip on the body. I was, and still am very impressed by the apparent quality of the workmanship on this knife.
The new AMK I have is actually an old design. The Shadow IV. It's a simple dagger with a Zytel handel. It comes with a leather sheath, though I think that AMK could have kept up with the times and built a kydex sheath for it. I handled one at around the same time that I bought my Quicksilver and liked it, but for various reasons, decided not to buy a dagger just then. When I finally got around to buying the Shadow late last year, I was rather disappointed by the quality of fit and finish. The zytel handle feels more plasticky in the hand than I remembered (but that could be just due to the rose-tinted glasses of hindsight). The join lines where the handle mould halves meet are very obvious and needed some work on my part to get it to the point where it didn't feel like it was cutting my hand every time I picked it up. Also, the AMK insignia on the handle looks very cheap. It is lightly stamped on a rough piece of metal which actually looks like tin.
