O.K. guys here is the scoop right from the Horses' mouth (I think I just called myself a horse, oh well).
After some extensive research and running more test (some even by me) this is what I have concluded about this fabric. First of all the samples you all have received are indeed lower than .8 in gain. I found out that our Tech Center made a test batch at a gain of .6 and that was inadvertently cut for samples. Therefore, nearly all of the samples out there are in fact this .6 gain. That is why some of you have made comments about it being so dark. The latest batch of this material made is in fact a .8 gain and correct samples will be available next week. (the roll is coming today) O.K. so that answers that question.
Now on to the contrast issue that we talked about when I was a guest on the forum.... After some extensive testing, we have found that the measurable contrast you get from this screen is better but only by a small margin. However, after talking with several industry pros (ie. ISF etc.) we have come to the conclusion that the perceived contrast level is indeed enhanced by this screen. The reason that this is so is because of the degree to which the black level is reduced. Think of it this way, we add black borders to all sides of our video screens in order to help the perceived contrast of the screen. If you take the screen and make the borders white, the image has not gotten any more dim nor does it have less contrast. However, when you add the black borders you give your eye a point at which to measure things by and hence you have a better perceived contrast. The HC Da-Mat works in the same way by reducing the black levels from a projector that indeed cannot project black (the absence of light).
I hope this helps to clarify some of your questions. Ken, does that help answer the e-mail you sent me?
Blake Brubaker, CTS
Vice President of Sales
Da-Lite Screen Company, Inc.