I have primed black with airbrush, basic colours are applied with airbrush and i have applied a dark grey shadow to all miniatures from the bottom of each miniature, all paintjob done after is brush work.
I couldn't have been more wrong then....
Having never used an airbrush I would never have guessed your technique.
It is very effective.
It has a very similar result to the method I suggested, although probably a more smooth finish is achieved using your modus operandi