zokissima:
No, I do not think a different skillset is required really; the principles behind the two are the same. To be completely honest, I love my Aztec, but with it varying both air and paint amount, I actually find it a bit more fickle, and the Peak, which functions pretty much as BGrigg and others have described dual-action airbrushes to have, I find that I actually have a far greater degree of usability, and a 'feeling' of greater control.
Emphasis mine.
This is why I keep saying this ability has dubious merit.
Zoran, you have a greater degree of usability and feeling of control, because you are using the airbrush as it is intended, which provides the maximum level of control. You feel in control, because you are in control.
Attempting to hold a trigger in a certain position for air, while laterally moving the trigger position for paint makes airbrushing so much more difficult that I'm shocked so many people even want to try to do it.
The vast majority of modern airbrushes expect the user to hold the air full on and adjust the pressure with a regulator of some kind, and MAC valves are nothing other than a form of regulator. Trigger on, pull back for paint. Don't like the results? Trigger off, raise or lower the pressure. Trigger on, pull back for paint. Repeat as necessary.
I'm sure some people can "vary" the air flow with a dual action trigger, but it's not designed to modulate air flow. I can make an light switch vary the flow of electricity by holding it so that is doesn't make good contact, and look, the lights kinda sorta dim, but that's not how light switches are supposed to work. They're supposed to be on or off. Turn on for light and off for dark. Want the lighting somewhere in between? Buy a dimmer switch, which is an electrical analog for pressure regulators.
I suspect that Azteks do have this "ability" as so many of them are mated to the Testors Blue Mini abomination, which doesn't come with a regulator, and therefore the user has 'some' measure of controlling the air flow. They offer a pressure valve and regulator as two separate items and want the Earth for them! Unbelievably Testors has all three items at the full MSRP of $285.97!