The only way to use light-rejecting screens is with long throw projectors, and you will have a fair bit of image degradation, and loss of viewing angle. I have seen the Elite Black Diamond screen with a high brightness (5,000+ lumen) projector at 110" and had mixed feelings.
First, the image was bright, it popped and held up well to the ambient light in the room (board room) it was in.
Second, the image had some hot-spotting from the gain it was providing.
Third, the image had significant sparkling around the image. This is similar to how light reflects off of snow - it sparkles a bit, and this screen emphasized this anomaly.
Fourth, the screen was pretty expensive for what it was.
I would NEVER use a ambient light rejecting screen in any situation where image quality matters. That said, typical PowerPoint presentations or a trade show are not 'critical' viewing environments. So, this screen was not only ideal in the installation it was a part of, but would be ideal in your situation with the following requirement: You MUST use a longer throw projector so that the angle of incidence between the lens and the screen works within the manufacturers tolerances.
Personally, I haven't tested a covered rear projection setup vs. a ambient light rejecting screen, but would think you would have very similar results, with lower cost associated with rear projection. Given the choice between the two, I would probably go rear projection. But, both setups have limitations, and drawbacks, but deliver a very viewable image in a less than ideal viewing environment. If you can't get 12'+ of throw distance, and have the projector near, or below, the top of the screen, then it seems like a light rejecting screen won't work at all, and must be eliminated as an option unless you really want to work to get the setup right. I would likely opt for rear projection in your setup.