Evan, great comparo. I would sell all my cars and bequeath my left nut to a castrated Pakistani sex offender just to have a FGT in my possession.
For the OP I will compare my 480HP (at the flywheel) Superformance replica to my daily driver '02 Z06 (humbly rated at 405HP at the flywheel). As a driver, I personally feel more confident being very aggressive with the Z06. The benefits of better tire and suspension technology, not to mention active handling controls, really allows you to explore the limits without getting yourself in too deep. This car absolutely rocks and I can only imagine what a C6Z feels like with an additional 100 HP and bigger brakes (most likely my
next daily driver once I wear out this one).
I can't say the same in the Cobra...It's as raw as a battle ax - the driving experience, that is (and it
should be that way). It's a magnet wherever I travel and the straight line acceleration (drag radial and/or Billboard stickies assisted) would beat my Z06 in any 1/8 or 1/4 mile test.
Not by much (maybe 3 to 5/10's, max), but it would still win. This car, even though fully sorted out, handles quite well. I just lack the self-confidence (and the wallet) to really see just how hard I can push it in the twisties.
Many a Cobra lover/owner gets wrapped up in the "romance" of driving one of these beasts. The real experience is usually much different than the dream dictates. It's not for everyone, but I have more fun bombing around town in my SPF than I ever did in the various muscle cars I have owned.
So my final vote (and answer to your question) is that modern muscle will beat the old Cobras more times than not.
-Dean