Epson Home Cinema 8500UB Projector Screen Recommendations
Let's start with the basics. The Epson projector has lots of lumens when you need them, for sports or TV viewing. And, of course that means plenty of lumens too, for movie viewing if you are willing to abandon "best" modes for a brighter, but still darn good looking picture. (Less perfect skin tones and color accuracy, but not bad.)
Where the Epson doesn't have a ton of lumens, is when you want the best picture it can produce. Even then, however, the Epson Home Cinema 8500UB is about average in brightness.
This can create a dilemma, to enjoy "best" mode, you can't go with an overly large screen. With a normal screen with gain in the .9 to 1.3 range, I'd say about 110" is as large as you want to go, to fill the screen, with enough lumens for good movie viewing.
Thanks to the best black level performance anywhere near its price, the Epson will match up very nicely with a white surfaced screen, and still yield very good blacks. I am, as usual, doing most of my viewing on my high contrast gray surfaced Firehawk, and with about a 110" size there, blacks are really very nicely black. The letterboxing is normally unnoticeable when watching a movie. I like that.
Consider your room. A high contrast gray surface will also help with "rejecting" side ambient light.
If your walls and room are inherently pretty dark and you have full lighting control, you can definitely go with a nice white surface. I must admit the Epson just screams, by comparison, when I use it in the testing room, filling my 106" Carada. We're talking about more punch. The Carada claims 1.4 gain. All I can tell you, though is that in that room with medium dark walls, etc. I do believe the Epson Home Cinema 8500UB could tackle a full 120 inch diagonal screen, with a plus gain surface like the Carada.
In other words, take your pick. If you are a black level fanatic, you'll love the HC gray screens, otherwise, the Epson has great enough blacks that you can go for the overall brighter white surface and its brighter image.