Depends. I would think with the Epson, in a room with fully controlled lighting, I would go white. The high contrast gray absorbs more light, but gives the illusion of deeper blacks by, well, being gray in a room with ambient light vs. more reflective white. That is why teh matte white will be rated around 1.0 gain, but the high contrast grays are usually 0.8 or less.

Long story short. If you can control the lighting in the room, then go white.

Farewell - June 4, 2020