This is a topic that used to come up frequently but has been quiet of late. Some people swear by them, a lot of people swear at them. I fall into the latter camp.
My experience is typical of many people's. I had an A430 that simply stopped working after a service life of at most twenty or thirty hours. I had meticulously followed all cleaning an care instructions, but the thing died nonetheless. I was able to return the body to Testor's for warranty replacement but during the three week turnaround, I picked up a Badger 200NH and have never used the Aztek since.
One thing to consider is the myth that Azteks are easier to clean than conventional airbrushes. For general usage, you basically clean an Aztek by blowing thinner through it without disassembling the tip, however you can clean a conventional airbrush in exactly the same manner. Thus for general usage, cleaning an Aztek is the same as a conventional airbrush.
How about when you need a thorough cleaning such as when the tip is clogged? Well you can unscrew the Aztek tip and soak it in thinner overnight which will hopefully fix the problem. Alternatively, you can pull the tips apart (they're not designed for disassembly, but with force it can be done), clean the needle and nozzle and after jamming the parts back together, you should be good to go. However, to clean the nozzle and needle of a conventional airbrush requires that you simply unscrew two or three fittings which are designed to be disassembled, clean the parts, and after reassembly, you'll be good to go. Thus for occaisional deep cleaning, cleaning an Aztek is more time consuming and difficult than cleaning a conventional airbrush.
My thoughts would be to look at a Paasche H if you want the ease of use of a single action airbrush and either the Badger 100 or 150 for the enhanced capabilities of a dual action air brush.