I have projector in a room similar to size you mentioned. Mine is 1080p though. feel it's more than adequate for a 120 inch screen and I don't feel missing any pixels. I kept it dedicated for movies only, feel it's not worth watching a tv on it, theres a lot of difference in watching a 24fps movie on a projector as compared to watching same movie on TV, though its just me. There's a feeling of cinema which tv cant give. I feel if you watch lots of movies/Netflix, a projector is best but just for watching TV only, I wont suggest a projector as source quality is very poor to be blown on a big 120inch screen. Also no matter what the projector, the lighting in the room needs to be controlled in order to enjoy, whereas tv can be watched anytime. In short, if you want to seriously enjoy high quality world of movies/streaming then projector is way to go, if just casual watching TV channels then tv is way to go.