I had an Acute Matte screen on my Hasselblad before I switched it for a Maxwell. There is no perceptible difference in brightness, that I could detect. They seemed about the same. I switched to the Maxwell to get the rangefinder split prism since my Acute Matte screen was a plain screen.
That is exactly my experience... no difference between Acute Matte and the Maxwell, except for the focusing aid. They are both excellent.