Chip, sounds like me writing at 3am. When I spray using FF210, FF211 I am on the door or trim, closer than 12", maybe 8" but its quick or as desired by the results. I can add that spraying steels and fiberglass first coat (prior to anything ever on the door) you might want to be back a bit and get a feel for your distance and how the paint wants to sit on the doors. Paint wants to run easier on fiberglass vs. a factory primed steel.
I really cant complain at all about my setup, I am happy with the lack of overspray. I can shoot 16-18 masonite MDF doors in a single room and you wont really see any overspray in the air except for where the gun is at that moment.
Spraying Benjamin moore 314 acrylics is a much different thing than spraying ICI Dulux 1407 semi-gloss for example. BM 314 will run like crazy and comes out of the gun twice as fast, its so much thinner to spray so that needs to be considered.