I agree with the comments about Candy. My stock Candy Jade Green had a duller hue, and the VMR paint had a very intense brighter hue, likely from a heavier application of the candy. I am not a painter, but I believe that results from the metallic are more consistent.
Because candy paint is transparent it is more susceptible to fade and oxidation which can dull it over time. Fading usually affects hue - causing the color to lighten over time and lose some of it's depth. Same with oxidation in the clear, the clear gets foggy and the color get's back-light less as light is reflected. Also older lacquer jobs can yellow further changing the color and luminosity.
Fresh candy looks intense and bright in the sun because the light hits the base coat and back-lights the color. Think of it like looking in a swimming pool in direct sunlight or how a candy apple looks like in direct sunlight.
It has a depth that is often described as "so deep you can fall into".
Metallics have their own lite reflection properties. Specifically how the reflection of light by the metallic particles can change the character of the highlights. Excluding flip flop, chameleon, mystic, or other color change paints (which rely on crystals rather than metal flakes), metallic can shift the color slightly as light hits it which is why a metallic paint car will look like it has dark spots and really bright spots depending on how it hits it. Metallic is also susceptible to fading and oxidation but the color is more durable and consistent.
Honda combined both for most of their paint jobs - candies were often shot over a silver or gold metallic base to get both the highs and lows of metallic with the brilliance of candy. Some great examples of this are Flake sunrise (orange candy over silver metallic base) and Candy Bacchus Olive (blue paint over a gold metallic base). Candy Jade Green and Candy Sapphire blue look to be shot over a very fine metallic silver base.
if you are going to do your own painting each has it's own pitfalls - metallics can tiger stripe or stick up through the clear, candies can run or clump and you have to start from scratch if you screw it up. If you are paying a professional make sure they are well versed in how to spray candy (most will know how to shoot metallics as they have been used on cars for the last 60 years). I think candies are high maintenance as compared to other finishes because of their nature, so you have to ask yourself what do you really like about the paint? the color? the depth? the shimmer?
