Just to add that while using a shorter throw might add brightness, by the same token it reduces contrast. Also, using more zoom in the projector tends to give a softer image as more area of the lens (and the A Lens) is used. If you can set aside a room for a fixed curves screen, then surely you can decorate it in a dark colour scheme, so lighting up the side walls (a curved screen will still reflect light to the ceiling same as a flat screen remember) is a minor consideration IMHO.
I think that it is more a solution when (as in many AV situations) we have to chose a compromise because the room isn't ideal in terms of size, layout and throw distance. I've seen a few thread lately about curved screens as if they are a means unto themselves, even if the user doesn't plan on having an A Lens. I wonder if there is another forum somewhere that has planted this curved screen seed for any use, or whether it's just coincidence?
I did find that my Lumagen gives a better result for vertical scaling than my projector, so no argument there.