I'm thinking about purchasing a Graco x7 airless paint sprayer. I have a Wagner Power Roller and it does a good job, but I'm just looking for something faster and easier, especially for ceilings.
My main question is how bad is the overspray? I know that you do have to mask, but do you have to cover the floor too? Can you work in sections and just move the drop cloth from one part of the floor to the other? Do you have to cover doorways to prevent the spray from traveling to the next room?
You definitely have to cover the floor completely. I always try to cover door hardware and run paper along window sills as well. Overspray/dust/bounceback has a habit of falling everywhere, and although it can sometimes be cleaned up fairly easily, I prefer to err on the side of caution. You probably don't need to cover the door opening, but it is a good idea to run drop sheets out of the room a ways.
Except for ceilings and new construction/total reno, I would not use an airless sprayer for interior work.