In 2007, I spent a weekend in Toronto at a Luminous Landscape workshop offered by Michael Reichman, featuring Jay Maisel as the main speaker. Before the workshop began, I was talking with Mr Reichman about his print sales in his gallery, and asked if the color of the matting that the image is displayed within, has any affect on his print sales. He said his prints ( regardless of the image displayed ) with BLACK matts, outsell all other by almost 10 to 1. He was so emphatic, that I still remember our conversation to this day. And all my prints in my home, since that day, get mounted with black matts. I still prefer the black matts.
Needless to say, I preferred the black/dark grey mode on Smugmug, and still do. I probably need to update my Smugmug display mode someday...
And I look forward to dark mode on my hand held devices as well.
I have used the black/ screen white text on my Kindle app in my iPad for years - especially reading in bed with the lights turned off. A bright white screen in the dark really is an anathema.