I think this was predicted, that the GT500 would be faster in a line and the ZL1 Camaro would corner better.
Though from the inside line article it pretty much states that the ZL1 Camaro was the better drivers car. They stated that it launched easier, shifted better, and handled better, and that on the back roads the GT500 couldn't keep up.
This was a same day, same driver test so it has the most merit of all of the GT500 vs ZL1 Camaro stuff that we have so far. Though should wait to see if this sentiment is shared among other testers or if it is just insideline.
They also stated that its ride was nicer to you then the GT500 but also stated that the GT500 doesn't beat you up either.
In other words the conclusion from the article is that the ZL1 Camaro is imply the better performance car.