I've got some experience on this and "Doc Martin's" (I think that's the name of them or "P.H. Martin's") for metal works better for a water-based acrylic enamel. Both clear coat well enough, it's just that the Createx is like spraying elmer's glue and doesn't reduce very well, even with their special additives. It can be made to work if you dial the pressure way up (I've tried it through all three of my Iwata's and my Paache-the cheapy Paache works better because of the big orifice).

Why not just get House of Kolor urethanes? You can get small amounts (1 or 2 ounce), but they're a little more expensive. They also spray fantastic.