Your opinion and that of a few other people on this thread have definitely confirmed to me that the P Zero Nero is not a tire that I want on my car, thanks for adding your experience.
In fairness, the Bridgestones weren't very good on the track either. I had mileage left in them, but wanted something track specific.
I'm leaning towards 660s. But after this thread may go Dunlop's just to try them. I've had good luck with their tires.