Has anybody used gravity fed airbrushes? I'm thinking of getting one because I don't do much airbrushing, but I would like to have the option available if I need it. I'm worried that a gravity fed will not work well and end up causing headaches. Does anybody have any opinions on this?

the problem is that you can't lay the brush down - you spill the color.

very good point. I hadn't even thought of that. I was more worried about the consistency in the paint flow rate.