Update: the tires were pretty good on the track, but I don't think they're as grippy as the Pirellis I used on VIR Full Course. They screamed a LOT, but it was the kind of scream that lets you know how close you are to the limit by the pitch of the scream. Didn't really notice the noise on the road that I had heard with the quieter (silver) car. Exhaust rumble drowns it out. The screaming & slipping didn't seem to get worse as the tires heated up - stayed about the same over the whole 20 minutes. Not a huge amount of wear, either. The outer edges on the rears wore the most (camber challenged), and the fronts were fine. Pretty sure when these wear out, they'll be replaced with a set of the Pirellis - then I can take them up to Patriot & thrash them & find out if my impressions were right.
I had a set of Azeni with me as spares, but I was too lazy to put them on for comparison - kinda wish I had.