There is a long, long way between a cave and a fully lit family room and the distinction is tremendous. As well, the tradeoff in image quality due to the optical properties required for ALR screens is significant. There is tremendous image degradation that ALR screens introduce to front projection.
In full disclosure, I have not personally seen and evaluated ultra short throw ALR screens to see if they have the same negative impact that I've seen from every other ALR screen I've personally laid my eyes on. Including Black Diamond, Supernova, and the DaLite/Drper offerings.
Assuming the same negative quality, then it becomes a question of how bright the projector is, how much light control there is in the room, image size, and content viewed while there is light in the room.
With side windows, a set of decent curtains are often all that it takes to block out plenty of light and leave a reasonably good viewing condition for sports, and general HDTV during the daytime.
Once it is dark, then the room won't have any outside ambient light coming in and it is no longer an issue anyway.
The tradeoff is that an ALR screen ALWAYS degrades image quality significantly. During the day, or after dark. It improves contrast significantly, which is great for non-critical viewing. But, if the point of getting the screen is to make critical viewing of movies better during the daytime, then you have to also take the critical hit of hurting image uniformity and adding sparkling to the image at the same time.
Or... get a set of good blackout shades, or some good curtains.
The flip side being that after dark, the curtains aren't needed and the image will be excellent, while the ALR screen will still degrade image quality.
On top of all of this, there are very few retractable ALR screens and they are extremely expensive. Finally, an ALR screen should be paired with a brighter projector to help with the drop in light output that ALR screens typically have.
With $4,000, I would always recommend that someone drop $3,000 on an Epson 5050, and spend $300 on a screen, and $700 on decent blackout curtains than spending $2,000 on a Epson 4010 and then dropping $2,000 on a ALR screen. The first setup will be very watchable during the daytime, and will be excellent at night. The second setup will be okay, at all times, with only marginal improvement after dark.
ALR screens were designed for boardrooms and sports bars, not home theaters. Their extremely inflated price point pads profit margins, but does not reflect that the installer actually understands how home theaters should work, and the client should always be aware of the significant pitfalls associated with using ALR screens.
AV Integrated - Theater, whole house audio, and technology consultation during the build and installation process in the Washington, DC metropolitan area.