Matte white is the most often recommended screen material for viewing in the dark with no ambient light in the room. The only thing that would make matte grey worth consideration is if room surfaces are light colored. With light colored ceiling, walls and floor, light from the projected image can be reflected back onto the screen (cross reflections) causing image washout similar to having a small light on in the room. Your dark grey room surfaces make a matte white screen the obvious choice.
Independent testing has shown that matte white screens rated at 1.0 and 1.1 gain generally measure roughly the same in the real world, so there's no reason to be concerned about a .1 gain difference in manufacturer specification. Silver Ticket is often cited as the best combination of performance and value in matte white screens as the screen review in thewirecutter.com (link below) documents. On the high end Stewart Filmscreen is often held up as the industry standard for those willing to pay a premium. There are incremental performance improvements available as you move up the price/performance curve. It's hard to predict how much money someone is willing to pay for each increment of performance improvement so that ends up being something each person has to decide for themselves.
thewirecutter.com/reviews/best-projector-screen/
Independent testing has shown that matte white screens rated at 1.0 and 1.1 gain generally measure roughly the same in the real world, so there's no reason to be concerned about a .1 gain difference in manufacturer specification. Silver Ticket is often cited as the best combination of performance and value in matte white screens as the screen review in thewirecutter.com (link below) documents. On the high end Stewart Filmscreen is often held up as the industry standard for those willing to pay a premium. There are incremental performance improvements available as you move up the price/performance curve. It's hard to predict how much money someone is willing to pay for each increment of performance improvement so that ends up being something each person has to decide for themselves.
thewirecutter.com/reviews/best-projector-screen/
