Get it. Easily my fav steel. Just clean it up after some use and a strope every week or so (if you use it daily / a lot). 2000 diamond cleans it well and I use green rouge on a leather strope. 20CV is very similar.
Pretty sure M390 is damn near identical to 20CV, at least in terms of composition. I’d recommend a much lower grit diamond plate though in case u need to do any real sharpening. 2000 grit might be enough for cleaning up the edge and touching up the blade from time to time, but in my experience M390 tends to be a bit of a pain to sharpen when it’s properly heat treated, and reprofiling can take a while. I’d suggest also getting at least a 400-600 grit, depending how u like your edge (mirror polish vs toothy edge, each has its own pros and cons depending on the steel and blade geometry).