Using the Carada calculator, with a throw distance of 12 ft. using the PT-AE4000U proj., the maximum screen size I can have is 88 inch diag. Carada has this in the exact screen size of 2.35:1. I think I would rather have the wider screen, even though narrower aspect ratios would be a smaller picture. Here's another option, get both size screens, a 2.35:1 and a 1.78:1 and swap between them. (Just a thought).
They have 3 different brightnesses with a gain of 1.4, 1.0 or 0.8. I'm leaning toward the 0.8 for extra contrast, perhaps. The 1600 lumen should compensate for a darker screen.
The projector central calculator says the AE4000 will be able to handle a 115" diagonal 2.35:1 screen at 12' throw. Now, you don't really want to max out the zoom, so call it 110" max.
This is 101" x 43", which would equal a 88" screen in 1.78 like you say. If you can fit the 101" wide (about 108 - 110" with frame) that would be a viable option for you. If you go into something like a 100" 2.35:1, that would equal a 80" 1.78, which is really getting kind of small.
Some people do get a 2.05 screen to split the difference, but then you will always have bars except on a few movies.
