I've been using the same Paasche H single action airbrush for decades now and have never really found myself wishing I had a double action until recently. Got a Paasche double action for Christmas, used it a couple of times, and I'm back to the single action. For my purposes, I guess I've just had a single action long enough that I know how to manipulate it to get the desired effects that I'm after...but then again, I don't really get all that sophisticated with what I do with it. With all that being said, I guess the main reason I went back to the single action is ease of cleaning. Mine is an external mix, siphon feed, so when I'm done with a painting job, I just take the needle, cap, and cup and drop them all into a pickle jar with MEK in it. Put the jar in my ultrasonic cleaner with a little water to transmit the sound waves, and turn it on for 20 minutes. Take the parts out of the jar wearing latex gloves, rinse under hot water, and they're totally clean. That process might sound complicated, but its actually really easy and only takes about 30 seconds of my direct involvement to accomplish. I've just never been all that enthused about the idea of flushing an airbrush to clean it, so this is what works best for me. Don't know of any double action airbrushes I could clean so easily without flushing.