Where have you read that you should get a 2.35 screen?
Were they talking to you? Or were they talking to people who have a lot of money to spend on their dedicated home theater setup?
Many movies are NOT shot in the 2.35 aspect ratio. Almost all games are 16:9 (1.78 aspect ratio), many movies are 1.85 aspect ratio, all HDTV is 1.78 aspect ratio... And most of all, the projector itself is 1.78 aspect ratio (1920x1080).
So, why is it again that you want a 2.35 screen?
When people are just getting into front projection they read a great deal about the 2.35 aspect ratio. There are tons of ads around 2.35 as well. It seems ideal, and is definitely cool. Ah, heck - it is cool! All you need to do it properly is a projector with motorized zoom presets, a room which supports a good 2.35 screen, and you are good to go. Well, except almost no projectors have motorized zoom presets... That's okay, you just need a good anamorphic lens and a lens sled. (several thousand dollars!)
What!?! Yeah, a good anamorphic lens is expensive, and the 'poor mans' zoom method is well beyond the capabilities of the W1080ST.
What you want is a 1.78 screen.
How big is your room? How far will you be sitting from the screen? How much conditioning of the room are you doing? Dark walls, ceiling, carpet? Sound treatments? Why the short throw 1080ST over the W1070? Why not the Sony HW40ES? Ceiling height? Room dimensions? Surround sound? Screen type?
There are times when I recommend a 2.35 setup, but they are far and few between. The 'poor mans' zoom method, as used by some projector owners is fine, but they could run a 16:9 screen of the exact same width, and have just as much of an appealing image for 1.78 content at the larger size.
Perhaps you should look into a screen with black 'snap-on' masking panels for 1.78 to 2.35 viewing conversion if you want to have a properly masked 2.35 image.
But, with the 1080ST there is no real way to properly get good 2.35 projection from it and still have a usable 1.78 setup, which will be needed.
