Very unexpected 296 GTB experience...CF wheels...

Were tires and tire pressures the exact same between the 2 296’s? You’ll notice that more on the street than the wheel weight difference.

 

The tire reviewer in the below link provides some objective data points and subjective impressions across three sets of wheel with vastly different weights (20, 38 and 52 pounds per wheel) but identical tires.

The takeaways -

Wheel weight has less effect on performance than expected: the reviewer calculated a 1.75 multiplier for wheel weight versus sprung weight.

Increasing per-wheel weight from 20 to 52 pounds decreased acceleration by 5.47 percent (the effect on cornering and braking were smaller than the effect on acceleration); a difference of a few pounds per wheel will have a small effect on performance for a street car.

The lighter wheels subjectively steered better than the heavier wheels; the caveats are that the testing was not blind, and the weight increments were much larger than the few pounds per wheel in this thread's comparison of CF to forged 296 wheels.

Wheel stiffness is more important to subjective feel than a small difference in weight.

The above chat comments pointing to different tire models and age being a bigger factor than CF versus forged make sense.