Well... most can be done through the scripting system...
I'd like to show you my setting... (for G25)
In the \data\script folder there is a file for each car which only contains one command like "run road" for every road car (lx', fz5, uf1.....), "run paddle" for the formulas and "run sequential" for the race cars.
Then I have three files named road, paddle and sequential:
road
/shifter shifter
/button 8 gear_1
/button 9 gear_2
/button 10 gear_3
/button 11 gear_4
/button 12 gear_5
/button 13 gear_6
/button 14 reverse
/echo Shifter Setup loaded
paddle
/shifter sequential
/button 4 shift_up
/button 5 shift_down
/echo Paddle Setup loaded
sequential
/shifter sequential
/button 9 shift_up
/button 8 shift_down
/echo Sequential Setup loaded
Those scripts just change the gear changing mode and the assigned buttons. Nearly anything mentioned here can be changed through the scripting interface. (like FOV, force feedback strength)
It's just not thaaaaat intuitive for users who just look at the menu