Henry I would not for one minute suggest that using air tools for sanding was hack work...it's not. For me, it's a matter of preference and the only difference is that you may use an air file to rough out your body work and I do it with my long board. Hack...not a chance nor would I suggest that it was. You do good work and I respect you for that.
One thing I will say though about air files versus long boards on large flat panels like a hood is the fact that you have less control of the weight of the air board versus a long hand held board. I have found in the past (and one of the main reasons I don't like using them any more) is because of the heavier weight and the speed at which it knocks down filler, it's much easier to over sand. A long board is slower but, I feel you have more control.
I hope you don't take offence to my opinion as none was intended. As I mentioned in "#13 permalink" about the elderly man that straightened out a Dodge Dart rear quarter panel with an 8 inch Hutchins Mud Hog"...I never got as good as that man with his air tool and really I don't feel that it's an art that I care to master. I'm only concerned about how straight my panels are using the tools that I feel I have somewhat mastered.
With all due respect.