New tire report
New GY Eagle GT's installed. These tires look great on the car and appear to be wider than the stock Potenza's. Noise problem is gone and I feel like we're finally able to enjoy driving this car again. I suspect the rear alignment had been "off" from day one (causing cupping) as they found the right, rear toe to be out of spec quite a bit as well as one side of the front to be out slightly. I had aligned the front previously at another business but I'm not sure they did anything with the rear.
As regards handling, I am very satisfied thus far with the limited driving I've done in one evening. Maybe I'll come back on and give another report after I've put about 10k miles or so on the tires.
Regarding the Potenza's (24k miles), one was down to the wear indicators, another was close, and the other two looked like they would go another 5k miles or so. I did not swap or rotate the tires as I should have, having only swapped front to rear once. The two more heavily worn tires had been on the front, where the weight is, much longer than the other two tires.
I'm not sure why some folks would only get 10k miles on the Potenza's, other than extreme driving, racing, cornering hard, etc.
I strongly considered the GY Eagle F1 A/S-C's, which would have been roughly $100 less due to costing less to start with and the $80 rebate (GT's had only a $20 rebate). I went with the GT's because I though they'd look better on the car and specs were very similar.