I am still pretty nervous with the rolling option but I am enticed by the $$. I painted a 1953 international truck a few years ago with tremclad green and it turned out surprisingly well for being sprayed on a gravel driveway....
I think the trick is in the prep, wet sanding and polishing. And of course the expectation level of the owner If I go ahead with it I will definitely try a few tests on something else first.
Pierre