Suggestion - go to a photography store and purchase an 18% neutral density gray color card. Take it to the paint store and ask them to match it, try a pint first. Be sure to request deep tint base, this will have more earthy tones than a light base which has the battleship gray look.
If you like the color, go ahead. I had it lightened up a little so the room was not too dark.
Neutral density gray reflects visible wavelengths relativle equally and will not change your perception of color from reflected light. Think of walking in to a room with 6500 K light in a white linen suit. Any color on the walls will be picked up in the perception of the color of the white suit. The gray will let the suit appear white.
Widescreen Review has a great write up on home theater set up on some of their back issues - most notably Imaging Science 2000.