I have a 2005 z 51 corvette c6 with my c4 cab porsche: the impression I have driving both is the following:

the porsche can be placed exactly where you want it to be the C6 can be placed within a few inches of where you want it to be which can get a little scary. The ride over bad roads is MUCH better in the vette and the torque leaves the porsche for dead however the porsche is better laterally zipping in and out of traffic than the C6. The run flats have been a blessing as they have prevented me from having to replace wheels that get bent or scuffed. I have replaced three sets of wheels and tires in the city in three years on the C4. I drove a magnetic ride car for a day before I took this one which is a six speed z51 car. the mag ride car does not ride as well as the Z51 which is actually more comfortable IMHO. I have found the c6 to be much more comfortable on long trips than the porsche and the seats are much better.