I've never actually seen MA on a 4k screen, but others have reported that it looks good. The polygon edges would be smoother, but you might need a microscope to see the difference
. The textures might suffer a bit.
By the way, my browser (Edge) seems to be having trouble with the Forum. Every time I try to answer a post, the Forum crashes (at least for me) and I can't get it to come back for several hours.