@fxrob
Felix, I absolutely concur with your opinion as art teacher, no matter the tool, it’s the person using it that makes the most impact on the outcome.
That said, I don’t have any experience with the Ultra but I do have plenty with several H&S Evolution and Infinity airbrushes.
To be honest using the 0,2 mm needle on the Evolution was perhaps the best experience I’ve had so far, but unfortunately the continuous use took its toll, even after replacing the o-rings both my evolution models never again worked as before, no matter how much cleaning and maintenance they got. That was the reason I came to buy the Infinity airbrush with two needles set.
The 0,15 mm has been the only needle I’ve used and I found it a much sensitive airbrush than the Evolution. However it also sprays beautifully, but the price tag is higher as you know.
This Christmas I got the new Gaahleri Mobius with the 0,2 mm needle as a gift and it also seems to respond well, but to be fair I’m still on the learning curve with this one.