I've got the mancave projector and I love it to death. But as for outdoors, whew... honestly I'd just get a big ole flat panel for that purpose. Two people can move them pretty easily and the whole screen setup, making sure the angle is right, enough lumens, etc... seems like it would be a chore each time. But don't let me be a wet blanket, maybe as BDV says, maybe there's new tech that makes it easier. My Panasonic projector is high def and all that, and it's not real small. But my Mom got a 60" Vizeo for some crazy deal and she keeps it on her patio! :-)
I thought about that, too. But, I dunno...the whole 120+ inches of screen thing just seems enticing.