I agree with the other posts that say "spray it out on a test panel and look at it before you paint the car". I suggest you put the same primer on that test panel as your car has on it before you spray the purple on your test panel.
The carbizole violet (main pigment in FC7) doesn't "cover" (aka "hide") very well, so you do get some of the primer's color showing through. What I mean is if you spray FC7 over light gray primer it will look lighter than the same FC7 sprayed over black primer.
I learned this the hard way when I painted my Roadrunner many years ago and I had all different colored primers all over the car. It took me 5 coats of FC7 before my eyes couldn't see the difference. This is one good reason to primer the whole car the same color before painting, especially with FC7.
Now to answer your question.... it is the pigment that gives the paint 99.9% of it's color, so the tinting of the paint itself by your paint shop is the most important thing.
In general, water-based paint dries slower than solvent based paint and also tends to have more "orange peel" than solvent based. On newer cars this isn't that important because they're all clear coated.