I just tried Parnelli's setups at both tracks and... wow big difference between us, no doubt!
On Seattle the car had a slow response, which forced me to antecipate my moves, specially at the chincanes. As you noticed i like a more "nervous" feeling.
Then all that brake power at the rear was another problem... i had to be carefull and not trail brake as much as i do with my setup, or i would loose the rear, specially at the strongest braking points.
Another thing was the gears, from 2nd to 3rd and from 3rd to 4th i think it looses too many rpms/power, i prefer closer ratios. However the 5th was a bit shorter than mine and that was good.
As a conclusion i think your setup is better for a more "relaxed" driving. Maybe to make endurances without making too many mistakes, even if i would take off all that brake power at the rear...
At Laguna things went better. The harder and lower suspension gave it a more "alive" feeling without getting "nervous" like mine. The gearbox still had same problem, loosing alot of rpms from 2nd to 3rd and from 3rd to 4th, but again the 5th was good.
The brakes were the same, too much rear power for my tastes.
At the faster corners i also felt a need for a bit more downforce at the front, to help cornering without that small understeer.
In the end, at both tracks i had to learn to drive your setups in a more "relaxed" way. I think your setup is easier for someone to drive without making mistakes, but if you make them it's harder to fix it.
I wasn't able to be as fast with your setup as with mine (about 2 secs difference), but might be because i'm not used to it...