, some questions:
Are the speakers going to stay there? Because if they are the screen would need to be Acoustic Transparent.
Can the ceiling hold a weight of 26lbs or more? Some of the projectors are heavy.
What kind of screen diagonal did you have in mind. Usually it's recommended that the image is projected on a wall for a few days/weeks to get an idea of what different sizes look like.
Will there be any instances with lights on viewing? If yes what percentage of total viewing time?
ALR screens can have visual artifacts such as hotspots and sparkle.
A better material, a longer throw range, a dimmer projector, and a dimmer projected picture can help mitigate or even eliminate the hotspot/sparkle.
Some ALR screens have a lower viewing cone. For the Cinegrey 3D it's 90 degress (45left, 45 right).
UST ALR screen will not have hotspot/sparkle (unless Fresnel type of fabric).
UST ALR's will do best in rejecting light coming from above.
The quality of an ALR screen versus a non ALR screen will depend on the quality of the material.
One option in this setup is a negative gain screen. With lights on, they will be less effective since the fabric absorbs light and spreads the result uniformly, it does not redirect it like an ALR would. The results are closer to neutral white screen/1.0 gain than an ALR screen.
A matte grey screen. Click the post to see the screenshots.
It's not worth getting a projector capable of deep blacks. Even the Epson 5050UB would probably be overkill from the black level standpoint.
UST projectors are ok picture quality wise.
A popular example of UST PJ and floor UST ALR screen. Ceiling drop down UST ALR screen also exist: