I am no expert but have done a fair bit of autobody painting. The metal flake, unless using large flake, will go through most nozzles. A couple of things to keep in mind when using any metallic spray paint is you need to keep it mixed all the time and ANY contaminant on your surface will act to change the surface tension of the paint in that area and will really show up in the finished product. The change in surface tension changes the metal flake orientation. I found that the finer the metal particle, the more this happens. This defect is called "frog eye blemish"
I have found that the candy metallic 3 stage paints are difficult to get exactly right as far as color. The Base coat color, thickness of application and even color of the primer all combine to effect the color of the final outcome. When I repainted my GL1000 and tried to match the original '76 LTD maroon color it was very difficult and found I had a new respect for professional paint shops. The equipment they use, the actual clean room quality paint booths and especially the knowledge, which takes years to acquire, justify the prices they will charge. I was quoted $1,400 for tank and side covers from a place that did show quality painting. At the time I thought the guy was nuts to charge that. After repainting the tank and covers myself, I understood why his prices were so high and they are justified.
You can do a decent job of repainting a tank yourself and it will look real good if you are careful and take your time. If you are looking for a restoration/show quality job, save yourself a lot of time and anguish and get it painted from a professional.
-P.