Been using a Badger for years. Worked okay but is getting a bit old and crusty. Kind of felt like it was never able to apply a light but meaningful coat ("light" always seemed to come out more mist than paint). Looking to cover body shell repaints, structures, track, and fine detailing when necessary. Pretty much what everybody in MRR uses an airbrush for. Scale is N. If I go with a double action I want to be sure I won't need the skill of a brain surgeon to control the paint flow.
I have not used Iwata, but the one that I thought would be most handy considering that I already have a Badger 155 Anthem was the Iwata with the side cup so that I could throw a little bit of color in a little at a time for weathering, etc.
I have the Iwata HP-BSC and I really like it a lot. Here is a link to all the different Iwata airbrushes: Iwata Airbrushes Main Page