I am seriousl considering the new In Focus Screenplay 4850. Its rated at 750 lumens I believe. How bright is that? I will have decent light control in my bedroom. No serious sunlight coming in.
750 is adequate. CRT projectors pump out around half that amount so if your room is light controlled then it certainly will be ok. As a side not, once you calibrate it and if you run in "cinema" mode then you will not achieve 750 lumens anyway from the projector.
I have been researching projectors for close to a year while planning construction on a new home. In that time I've found 750 lumens in a light controlled environment is good but it may need to be better than " no direct sun light." You may need to utilize the good old in home trial.