I currently have a Vutec curved screen (purchased from Joel Cohen at Hi-Rez Projections - no affiliation other than satisfied customer). The URL for their screens is http://www.hometheater1.com/,
then click on Screens from the menu on the left. I don't know if it's a toroid shape or not though, but it's curved both horizontally and vertically. I can take some measurements if anyone is interested. The corners are about 3.5" forward of the center of the screen. I believe that the surface has a gain of 12, but the new ones are ultra high gain Al foil with a gain of 13.2 Here's my setup for the following observations:
9" tube Sony projector. Made in '89, no burn in, digital chassis/convergence
Ceiling mounted projector, directly over the main viewing position, 11' throw
Small room: 11'x12'x7.5', white ceiling, light carpet, lots of light reflecting surfaces
70"x52" high-gain curved Vutec screen
Room can be completely darkened, but my wife likes a little light on
ATI All-in-wonder Radeon powered HTPC
1) The screen is silver with no texture. I use a swiffer (synthetic dusting cloth) to dust it and diluted Formula 409 if it gets really dirty.
2) It's bright! I don't have any way of measuring it, but the 11 year old tubes still put out a lot of light
3) The center is brighter than the corners. I believe that's because I'm not sitting at the focal point of the curvature.
4) Flat field full white shows a slight color shift - the right has a very light blue tinge and the left is slightly red. I think there's a vertical green tinge directly in the middle, but it's so light it's tough to see. None of the aforementioned are even slightly visible while watching any program material.
5) While displaying flat-field full-intensity white, a paint chip of Baer's Ultra Pure White satin paint (the brightest Home Depot sells) looks mid-level gray compared to the screen. I can take a digital picture for comparison if anyone's interested
6) I can barely converge the projector to handle the curvature of the screen, but when it's right, the image is perfectly rectangular from my viewing position (on-axis). The further you go from on-axis, the more the curvature becomes apparent.
7) Audio is a problem. Whispering in the main seating is really amplified and there was a lot of reflection between the screen and the hard wall behind the main viewing position. 4" of Sonex wrapped in black felt hanging away from the wall behind the main viewing position helped significantly.
8) Light reflection off the back wall was a problem as well. The black bands from letterboxed movies became noticeably brighter than the black wall behind the screen when the average picture level was high. The problem was light reflecting off the back wall back to the screen. The black felt around the Sonex helped considerably.
9) Off-axis light rejection is excellent
I'm considering a larger, 16:9 screen to replace the current one. I'd buy the larger curved Vutec, but I'm concerned that I may not be able to converge the projector for the curvature in the corners at 80" wide.
HTPC: 650MHz PIII All-In-Wonder Radeon & SB Live!
Systems Engineer - Graphics and Video