Overspray is a fact of life with any spray paint system. Be it HVLP or
rattle can. So don't think you can spray the door in the house.
I've used Wagners for years, with success. The new one is better, and
the top line units can handle unthinned latex paint. Though like
another lister, I find thinning it a bit works better. The two power
selects are nice for detail work.
Cleanup is a pain, and takes a lot of time. Enough that I would
consider it not worth getting together just to paint an interior door.
I'd be looking at rattle cans instead.