On the other hand, the VW70's black level performance is one of the best. People wanting larger screens - say 110" diagonal, or a touch larger, may choose to go with a positive gain screen - there are a number available with gains in the 1.2 to 1.5 range. This will increase brightness, but as you get up to the 1.5 gain, you will likely notice a little drop off in brightness in the corners (that's on top of the slight loss all projectors tend to have, just due to optics not being as bright in the corners).
I generally am not a fan of real high gain screens, say 1.8 to 2.5 gain. With these higher gain screens, the viewing cone - the best place to sit, gets pretty small, and there is more roll-off in brightness. If you must go large screen with the VW70, you'll probably need the extra gain, but that's a really good reason to consider another, brighter projector, and there are a number of excellent ones to pick from.
I liked the performance of the VW70 on my 128 inch Firehawk screen (high contrast gray), but it felt just a little underpowered, when I filled the entire screen (and thats with a new lamp). I was more comfortable with it around 110 inch diagonal.
In my testing room, filling just all of my 106 inch diagonal Carada Brilliant White (a claimed 1.4 gain), the Sony looked very vibrant. I like my black levels a little lower, but I can't argue with the match, it looked spectacular on brighter scenes, and did a good job on the darker ones.
Bottom line: Pick your screen based on your room conditions, and whether you are willing to sacrifice some brightness for lower relative black levels.