Here is a good site that explains the advantages and disadvantages of different screens. http://dazian.com/html/audio_visual_intergration.html
The Epson iris and picture mode (off, video, movie) is turned off in the default setting. Setting it to picture mode and turning the iris on, and setting it to movie mode improved the contrast of the projector.
I have mine it the basement , with total light control. I have the homemade screen(all white) and will purchase a screen after a move ( waiting for job transfer).
I will probably purchase a white screen, as I think that the grey screens were used for contrast problems in older generation projectors. I may go with a larger screen and I think the white might give a brighter picture without resorting to a higher gain screen which can decrease the angle of view.