I'm projecting onto a wall painted in a matt blue/grey colour, so I would not think that that is very reflective. Not ideal without a proper screen but the picture is great (at least compared to our old projector). The width of the projected image is 220cm. In the settings there is a 'light output' setting which you can set to 50% (the lowest setting). There is a separate 'brightness' setting which you can turn down, but that then seems to affect the contrast. At the moment it is just a bit too bright... even reading subtitles gives me a headache. Any ideas welcome!
I agree for certain movies and in a dark room turning down to 30% or 25% would work. Not sure why 50% is the lowest output. I got some max contrast paint from screen goo which is mid grey and that help. Much better than a white wall. You need a litre though for 120" minimum and its a bit pricey although worth it.
What settings do you use? I created a thread for setting but not had any replies yet.