The difference in resolution is definitely appreciated. I have a 119" Draper onyx screen. I'm noticing the games are more immersive because of the clarity and lack of artifacts and aliasing issues on the PS4. I have a Sony HW30 LCOS projector in a light controlled room. This is a good low lag projector that kind of does it all.
If you are looking to go the projection route, you won't want to go back to your tv. Even my 58" plasma seems small when i play my PS3 on it in the living room.
Playing games like COD do take some getting used to though. There is just so much more to take in.
A projector set up is good for split screen gaming too. My wife and i have been playing the new lego marvel game and it is a lot easier to see what is going on when you are splitting a screen 8' wide.