My Aztek experience with an A430, almost the same thing as the A470, is nearly identical that of Darren. Since I had followed all cleaning and operation instructions, and it died anyway, I really would avoid it on the basis of reliablity alone. Additionally, it seems that Aztek's marketing is based on the premise that it is easier to clean an Aztek than a convetional brush, but that really is not the case. For the simple "spray thinner until clean", the level of effort is identical. If a full break down is needed, it is actually a lot easier to break down a conventional airbrush than it is to disassamble and Aztek tip. As far as painting, it displayed no particular adverse effects with enamels, although I too had a spitting problem, which seemed to be caused by paint collecting on the tip, perhaps due to it's small diameter at the end and the close proximity of the needle guards.
I have a Badger 200, which is basically a single action version of the 155, sharing with it the needle, tip, and air-valve assembly. It is an excellent airbrush, and my biggest complaint with it is tth awkward angle that the siphon feed color cup sits. I haven't tried ultra fine lines, but it is up to the task of free hand camo on 1/72 German armor, so 1/48 aircraft are no problem. Although I personally disagree with the trend toward neatly shaded panel lines, it's fine line capability would be more than adequate for that task. Considering how big some 1/48 planes can get, with the needle opened up, the thing can spray a nice wide pattern for overall coverage.
I have no experience with the Badger100, although I've read many highly favorable comments about it. Given the potential size of your model building subjects, one thing that might be of interest if Tom or another Badger100 owner could speak to, would be how wide of a spray pattern it can deliver.
Andy