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Nowhere do you specify how you made your measurements, what equipment and how the equipment was calibrated. Did you do this yourself. I have seen Stewart`s test results for both materials and the a list of the ewuipment used and its calibration including reference standards.
There is so much left out of your article that it become misleading. Mike is right on target and your response is inadequate.
The primary consideration in choosing screen gain is getting the brightness one desires. This might not be possible. Second is getting an acceptable black reference value. This was the reason for the .9 gain of the Da-lite. It was designed in conjunction with Joe Kane and Joe wanted a screen material that on smaller size screens (say below 120~ diagonal 1.78) would give him acceptable blacks with the Samsung SP-A800B projector. This required going to 0.9 gain. For larger screens, a gain of one would be more appropriate.
Now there is more to viewing hangles, half angles, yada other than just overall screen gain. For example, Stewart Firehawk has a positive gain below but fairly close to that of the Studeotec 130, that does a much better job of dealing with extraneous light and screen reflections from walls. But like any other material that is not a perfect flat surface, gain og 1.0, there will be adverse as well as positive effects.
Substrate material and sprayed on coatings. And one must deal with light spread on the screen surface. How does say is a single on\off pixel line look? Sharp clear or is there bleed? There is a lot going on and there clearly is not one correct answer or only one or two parameters that matter.
Studeoteck 130 was developed for CRT front projectors. Gain was despatrely needed for almost any size screen. 1.3 gain was chosen as the limit because any higher gain hot spotted. Certain colors also needed a boost by the fabric.
Everything else being equal, a black pit, a fabric with no sprayed on coating will be best with a well constructed uniform substrate construction. However, if your projector doesn`t have great blacks, most don`t, a negaticve gain substrate may be required. There is a lot more to discuss.
I think the only conclusion one can validly draw from your review has really notyhing specifically to do with the three materials being discussed. If you have light surfaces in your room, do not get a unity gain or close screen. Choose a screen material that will throw less light to the reflective surfaces and accept less light back. What you need to learn about is the effect of sprayed on particulates over the substrate material. Eliminating those is a major benefit of going to unity gain. But you can`t negate the choice of a preoper substrate material and its production tolerances.