An important thing to consider when talking tires and ZL1 coupes, is Performance Traction Management. I spoke with the engineers who worked on this system when we were in Virginia last February:
It's important to note that PTM was designed explicitly with the F1 G:2 Eagle's in mind. Swap them out, and you're going to lose some functionality of PTM, because it's not calibrated for any other tire. There is no "gaining" functionality with PTM. How much you lose is unknown, though, and depends entirely on the tire you've put on.
I bring this up because the only other car people that have to think about this...is the Corvette ZR1 owners/racers...and I don't think we hear much from many of them...
...of course, if you don't care about or use PTM...disregard!
I would look into Michelin SuperSports personally...have heard many good things about those. But I'm very impressed with the OE tires; impressed enough want to replace them with OE tires, again.