I have a LT150 that I ceiling mounted in my HT. I was projecting onto a white wall, which looked great at night, but was washed out during the day (I don't have much lighting control in my HT). I've heard lots of good things about the Dalite Model B High Power for the LT150. My configuration is such that the projector to center of screen to eye angle is 19 degrees. I called Dalite to make sure this configuration would work, as I've also read that the High Power was not necessary good for ceiling mounts. I was told that the viewing angle was 25 degrees, and I was well within that range.
After receiving the High Power, I got NO improvement in brightness compared to my white wall, when viewed either at night or in daylight. Moreover, a blank sheet of white copy paper appeared brighter than the white wall AND the the High Power. I called Dilite to find out why. I was told that I should be getting over 1.6 gain at that angle, but they could not explain why my white wall was equally bright, and the paper was significantly brighter.
In addition, my HighPower was defective, in that the left side of the screen was about 2" longer than the right side. This created (or made worse) some wrinkles that caused very disconcerting motion distortions during panning motions.
I purchased the screen through Cousins Video, who was more than willing to replace the defective screen with a new one. However, since I got no brightness improvement, and I've since read the Model B's are prone to wrinkles, I decided to return it. This was a somewhat costly mistake (20% return charge, $52 shipping UPS ground, plus installation time and hardware).
The moral of the story: The High Power does not seem like a good screen for ceiling mounts, unless your viewing angle is <10 degrees. I also don't believe the verbal specifications I got from Dalite are correct, which they could not provide to me in a printed/online format before or after purchase.
I'm now back with my very flat, white wall, which looks great with my LT150 from any angle.