You touched on the underlying question I really had. I have a ZT0562CF with CTS-204P. I really love the steel. It takes a while on the Wicked Edge to get a burr but it's worth it as it holds an edge nicely. I also have a Benchmade Ritter Griptilian with M390 and that takes almost no effort to get a burr and it doesn't hold an edge nearly as long. At least it's a pretty knife with my Death Grips custom scales. Both are sharpened at ~17 degrees/side. I was hoping someone would comment on the M390 from ZT about how it holds an edge with just general day to day use compared to Elmax.
M390 and CTS-204p are pretty much the same steel, so I'll just be referencing M390 here, to save any confusion of using both names.
M390 has a pretty annoying heat treat process to it, and that means that some companies bet better results out of it than others will, and that's just the fact of the matter. Honestly, Benchmade has some issues with their heat treat of M390, and generally you will find it running much lower than it should be on the Rc scale, and not optimally treated for toughness either, so you end up with a not-so-great steel, at least compared to what it SHOULD be.
ZT has also had some issues with their heat treat on Elmax, but those have pretty much been sorted out from what I've heard.
That being said, I've never really had an example of Elmax from a production company that was able to utilize the full potential of the steel honestly, because it is not a steel that does well when it's heat treated in large batches, but it is still a decent-performing steel overall from ZT now. I still think, as far as production companies go, Microtech probably has the best heat-treat for Elmax, at least in my opinion/experience.
As far as a comparison between M390 and Elmax, they should be very close to one-another, at least if they were both optimally heat-treated...which they rarely are. So, I'll only be talking about the M390/CTS-204p and Elmax that I have had from ZT from this point on, which have notably different levels of performance in my experience:
I have seen good things from the CTS-204p/M390 that I have had from ZT, and I will say that it will definitely out-perform Elmax in terms of edge retention, without a drastic loss of toughness, and actually is more corrosion-resistant than Elmax in almost all cases.
M390 is also a much finer steel than Elmax, so even though it has higher wear-resistance and should be harder to sharpen, it really doesn't take as much more time and effort as you would think it would compared to Elmax. It can also come to a much finer edge, and hold that fine edge for much longer than Elmax will. Elmax tends to become somewhat toothy rather quickly, like many high-carbide steels to, but M390 will do that more slowly, while being very aggressive when cutting.
In fact, M390 is one of the MOST aggressive steels I have EVER handled, even with an extremely fine bevel on it. That is to say, it will cut with very little effort into material, because the carbides in the steel are kept very small, and very even, so that even on an extremely polished edge, the edge is made up of almost entirely carbides, which cut extremely aggressively.
I personally like M390 more, though, again, both steels are pretty good. You really won't/shouldn't notice any drop in toughness from Elmax to M390 with how ZT treats both, so I don't see a reason why you shouldn't pay a little more for overall better performance.
