I have them. They get dusty at about the same rate as a pure black fan (which also shows gray/brown dust quite easily). I need to clean mine about every 6-9 months to keep them looking good enough to "show off". I generally run a Winix HEPA filter in each room of my apartment.

I don't think matte white is worse than matte black in terms of showing dust. They both do.

I suspect there's a reason brown is Noctua's signature color.