I had the exact same decision to make a few months ago. The Z06/Viper was not going to be my daily driver, but I did want to drive it to work from time to time. I could not get over the hot cabin, higher price, and sound of the V10. Yes the Viper has exclusivity, but I love the looks of the Z06, the options available, better gas mileage, more comfortable cabin, sound of the LS7 and overall better performance (turning and breaking) of the Z06. I have been enjoying my decision ever since

 

Gears would be good to add too imho. Z06 has a gearing advantage as well as the obvious weight advantage on the Gen III's. All the above mods plus the gears would be a perfect low cost modded snake and be a match for a bolt on C6 Z06.