If you have a gallon of VU, I'd just use it up first. The EM9300 is a better product in most ways, but not enough to throw away a whole gallon of paint. It also works to use the VU for your initial sanding coats and color coats, and then just do your top coats with the EM9300. That's kind of better in a way, 'cuz you're using the less expensive product for the coats that "don't matter*". The strength of the EM9300 is that is sprays more evenly out of the can and dries to a harder finish for buffing. In other words, its a better
finish.
*Obviously, these coats actually do matter. I'm just adding quotes to emphasize within the circumstance of mixing paints, using the less expensive paint for an undercoat makes more sense.
I use the Createx 4050 when I'm mixing colors with Createx products. I've mixed Createx products with other clears, and while nothing overtly terrible happens, the little shiny particles in the metallic colors don't get distributed as evenly within the finish. Other than that, the 4050 is good stuff. It looks and smells pretty much the same as VU, and it seems to dry pretty hard. However, I haven't tried using it as a top coat and buffing it, and I don't know that I ever will. Of the paints we've mentioned here, the 4050 is the most expensive of the bunch.
I imagine that Createx recommends the two-part automotive-grade top coats because they're selling their stuff to automotive guys. I haven't tried spraying a water-based top coat over the Createx Candy2o, but I know they do recommend using 2K clear for that. I did once get a drop of water on one of their Candy2o finishes and all the dye bled out. I had to do the finish over again! I know somebody here claims to have successfully sprayed VU directly onto a Candy2o finish, but I'm not sure who that was. Perhaps that was you,
@Matt Liebenau?
Thx!
That's a good question! Sorry I forgot to document that. I primed the body with clear, masked the binding with tape, pulled the tape after spraying the color, and used a fine half-round file to clean up the binding. A sharp razor blade works too, but files are kinda my go-to tool for practically everything. A file is just slightly less awkward to hold than a tiny, sharp blade.