3D And Choosing a Projector Screen
3D Screens: With active shutter glasses (as are all the home theater projector solutions so far), almost any screen will work. I'm told there are some slight differences, but haven't heard of any real issues.
With 3D, the key issue becomes having a bright enough image. True, ambient light still comes into play. As a side note, the glasses darken the ambient light as well as the image, (just not as much).
With 1706 measured lumens in our "tuned" Dynamic mode, the picture's rather good in 3D! Figure that the image to your eyes is about 1/3 as bright in 3D. That makes our 1700 in 3D, the rough equivalent of watching 2D at 570 lumens.
Well, 570 lumens is only about 100 lumens less than running 2D in "best" calibrated mode.
Thus, the Epson Home Cinema 5020UB 3D "brightest" mode has the horsepower to handle most of those 100" or so screens with respectable brightness, and be a bit dim with larger screens the size of my old 128". Currently I do my viewing in an all dark surfaced room, where filling my 124 inch screen for 3D provides an image that could be a bit brighter, to make me happy, but is certainly watchable.
So, in figuring your screen size, you might, if you want to max out for 3D, (depending on your type of room - cave or not), opt for a little more screen gain. a 1.3 or 1.4 instead of a 1.1, or if you are going gray screen, perhaps a 1.1 instead of a .8.
The Epson Home Cinema 5020UB 3D image is as bright as you will find on any quality home theater projector. There may be a few sub-$1000 projectors that are cross-overs that might be a touch brighter, but those aren't refined home theater projectors - no comparison.
I'm not a fan of the brighter high power screens like the Da-lite 2.5 gain, but it does provide lots of extra brightness. Too narrow a viewing cone for my taste, and too much corner roll-off.
Another option, budget allowing, is go dual screen. Park a pretty high gain screen on the wall, and then add, in front of it, a lower gain screen for 2D viewing. Whatever makes you happy.
Your room is, of course central to any decision. Choose wisely!
Note, if buying online, there are a number of well respected dealers out there, selling projectors, that have a knowledgeable enough sales staff to really assist you with screen selection.
I'm a big fan of "AV" type dealers. When I owned one of the larger AV dealers, our sales and support folks knew the products, knew screens too. All of the dealers currently advertising on my site in the US, were major competitors of ours "back in the day". They too were well staffed with good folk most of whom who knew their stuff. I think you are going to have to look really hard to find serious expertise on Amazon. Good shopping.
PS. Motorized vs. Fixed Wall vs. Pull-down Screens.