Yes, that is a very good point. Any effect can be overdone, usually with regret. As I was scanning the world with my camera a few days ago (what else do you do when you're sitting on the porch in the sun?) I found I could get the greenest, most incredible grass... except the black parts of my black and white dog looked like black holes. Pretty much pure black. Backing off the polarizer a bit restored enough reflection to bring back texture and detail in his fur. The point being that while you're busy being impressed by amazing color, you may also be stripping necessary highlights from the picture.
Anyhow, give it a go. Porta, Ektar, Gold 200, whatever. Doesn't matter. It'll all look good if the subject is right.