I don't have alot of experience spraying cars, and I've only used Dupont products for the finish coats so I can't be too much help. I've sprayed catalyzed acrylic mostly, but my first car I sprayed with urethane and I liked that very much. Urethane is supposed to be much longer lasting and give a higher shine than acrylic, so the next time I paint a car to be pretty I'll probably try that stuff again.
My problem is that I hate bodywork so much I know that I'll never get it smooth enough to make anything pretty, and then when you've got something pretty you're always worried about parking lot dings, key scratches (unintentional and otherwise), matching for repair, etc. Pragmatically, an ugly car makes much more sense, but that's not what you're asking, is it?
...but I've got to paint my engine bay and do a few touch-ups on the Canuck this spring/summer. I'm replacing the inner fenders and hope to get everything looking spiffy for my new engine. If the tax man is good to me this year, I'll finally have enough air to power my spray gun and be away to the races.
