2020 purchased the well-known single-action Paashe. Now using it to paint tracks, turnouts & bridges. It is a good simple & reliable tool. The paint bottle size is a plus for larger paint and multi-component projects. It can paint details weathering and so on.
But gets a bit crazy judging the amount of paint for a project. Over or under-mixing the paint, two constants not enough, or dumping leftovers.
Having used a full-size Iwata HVLP best of brand hands down, ordered the airbrush. Received it held it in my hand, back in the box, and returned it, pencil-thin was not cutting it for me.
Reading a similar thread the Harder and Steinbeck double action was mentioned Ultra 24. Doing some research discovered an unusual and impressive feature.
The trigger has a rotating collar with detents that control the fluid delivery. Examples are primer, top coat, 3 settings detail, fine, and dusting, 5 total settings. These preset the maximum fluid flow for the setting.
This is a unique feature, to say the least, and no others have this. Just over 120 bucks you really cannot go wrong, the brush is physically about the size of the Paashe, but heavier.
The compressor & having air tools it is outside, 2 stage 60gal tank. Can do a lot of airbrushing and it never cycles.

Pep