What? that makes no sense, I thought it was only the HP figures that mattered....
Seriously, of course you are right, but if you do enough track days, you ultimately can get sessions with good drivers on different cars, with relatively speaking the same mods (tires/brake pads) and it becomes very clear either who has the better car or the better driver.
In my experience, the good Porsche drivers buy either 911 2S or the GT3's, not the turbo's or 4S. Deep down, they will tell you they call the turbo guys posers. The really good vette drivers get the Z06's, not the ZR1's and deep down will call the ZR1 guys posers. Lastly, the GTR drivers, well I have not met a good driver yet that has kept the car more than a year (was too boring for them and did not require their skills) but the car is incredible and amazing at making poor drivers feel like they are good. Have yet to meet a good driver of a Lambo or R8 yet and thus their cars get eaten up on the track. Again, I think more of a statement of the driver vs the car.
And to be completely honest, the Viper owners have a reputation of talking about HP figures and racing down the straights, but no skill at turning and thus resulting in wrecked cars or minimum going off track. I can't tell you how many times of showing up and people getting nervous there will be a problem, purely by the reputation of the car. Then you get the comment, "oh, you can actually drive it. Seen too many who can't..."
In some respects, you see the same representation on the forums. Guys asking for more HP but yet don't know how to even use what they have. Maybe just a different make-up of people, but true Porsche guys get excited about better handling, braking, less weight, Not HP. And those particular guys seem to really wheel those cars around the track.
On the track, after you get to a certain level, things like the driver, downforce, tires, etc. make a huge difference--not just the OEM aspects of the car. Also, I have seen plenty of very fast GTRs on the roadcourses. Even 9114s cars have been very fast. For a real comparison, you really need OEM and a pro in both cars after some practice in both cars.