My room is not perfectly light controlled, so even at night I have light issues...primarily due to projector light bouncing off the screen onto light colored walls and back onto the screen to wash out the blacks. I can't comment on other white screens but mine was easily washed out from reflected light. The 4.0 (approx.) dark SF looked way better than the matte white screen during the day and just got better as the evening set in. Also, I only had the screen up for 24 hrs. before it came unglued so any improvement from "curing" was yet to happen. I watched the Bills/Steelers game 2 hours after I finished painting it. After the game I played a number of my films that I consider eye candy and was impressed.Awwww sheesh.
...your "50% better in the dark" statement / evaluation really flies in the face of some remarks made by a few who state that no Ambient Light "Gray" Screen can...or would outperform a Matte White surface in true controlled lighting.
P.S. Mississippi Man, there is one film you probably have never heard of that is a challenging test for any home theater set up. It is called Appleseed Alpha. The opening scene takes place in a subway and is very dimly lit...a very low contrast I played this on my "new screen" and while not perfect it was substantially better than my white screen. If you ever want to truly test SF, try that opening scene. As the subway train comes toward the viewer there is a door on the left. Check to see how many details you can make out of that door. On my white screen, no matter how much I adjusted my projector (Panasonic AX200U) that door was just a gray blob. On the SF screen I could actually make out some details.
To me, the test of a great screen/projector is not how it works with highly saturated or bright films like Finding Nemo or The Incredibles, it is how it handles shadow details such as the one I mention.