Lee,
did the harlequin thing a few years back on my jet, a Razor, great product, easy as any metalic paint to apply. It is a base clear process, so you will have to apply clearcoat follwoing the harlequin, within 24 hours recommended. The color shift is not dependant on thickness, i.e. number of coats, but coverage is. I put two coats on my Razor, looked great in the paint booth. Took it outside in the bright sunlight and I could see some of my gray primer underneath. A third coat and that resolved that issue, full coverage, and incredable color shift.
A cheap trick used by some is to apply a base coat of the primary color of the harlequin to cut costs, only applying one coat of harlequin. Your color shift will be reduced as you see the base color between the harlequin coat. Ugly affect, especially in sunlight, but acceptable under floruescent lights. Truth is, a good xyrillac paint can give you a better color shift when you cut cost this way.

Jim Hiller