How do I choose between Grey and High Contrast?

Grey and High Contrast Grey are both  have very similar properties. Both screens are designed to carry black shades even in situations where the lighting is less than ideal. 

The High Contrast Grey is much darker than the Grey, which allows for a better viewing experience in theaters where there is little to no control of lighting and/or natural light spilling in. Great for family rooms or entry level home theater enthusiasts. It can be played in the daytime or the nighttime. This screen supports projectors with a very week contrast.

The Grey screen is much lighter than the High Contrast but still is darker than the white, which gives it still the ability to hold those black levels. The Grey is ideal in theaters that have mostly control over the lighting, but still want to have lights on for other activities while viewing. For instance, playing foosball and eating food while projecting the big game. This screen helps support projectors with mid-range contrast levels.