I find myself in a position to comment on this as I have had experience in several of the mentioned cars. I have a bit of track time including schools in the C6 ZR1, C6 Z51, C6 Z06, and C7 Z51 and hope to have some time in one of the new Z06s soon. :thumbsup Here is my opinion based on what I have experienced.:wink
We owned a 2012 Centennial edition Z06 with Z07 package and carbon hood. I spent a lot of time tracking with this car so I know it very well. It was brilliant, and much, much better than the C7 for track use. I almost wish we still had it. I never got an exact weight but it was about 3100lbs. There was a very big difference in the pre 2012/2013 magnetic shocks because they were not available with PTM. In 2012/2013 PTM became available in the Z06 and the magnetic shocks were calibrated to work with the PTM system just like the ZR1. In my opinion, (and several magazine articles), 2012 is when the Z06 became a much faster and better track car than the ZR1. This system is what is being used in the new C7 with the electric diff (not impressed). The tires are narrower on the C7 than the C6 and again in my opinion, most of the performance increase over the old C6 vs the C7 is in the PTM and the new special tire compounds. You can literally mash the gas pedal to the floor before the apex and it will accelerate faster than a pro driver could do on his best effort.( not the same as being faster than a pro driver) :biggrin No more twitchy handling or throttle over rotation. This is not interference but truly an aid to make sure you got the best results and was certainly much safer than without it on such a powerful track car.
If I were looking for an ultimate track / street car, to me it is a 2012/2013 Z06 with Z07 and PTM. We have enough hot days at SM to witness SC and Turbo cars heat up and lose power including ZR1s and I am certain the new Z06... and my bet is that with same tires, the 2012/2013 Z06 would be faster than the new one after a few hard laps just like it was faster than the ZR1.
A couple more observations, 2012 and 2013 Z06 engines seem to have all of the valve and rumored bearing problems solved as well as upgraded cooling and a bigger dry sump tank to help with oil starvation on hard cornering. The Z06 engine is very good, and even though you can pull more power, they do not seem to hold up well to mods.
Hope that helps...:biggrin