Revised my conclusion: 1.
At 80 km/h it may be of lesser significience if you have 6 kg of lift on rear or -6.6 kg DF.
2.
At 140 km/h it definitely matters whether you have 18 kg of rear lift or you have -20 kg
of downforce instead, even more if you turn in and have still your foot on the brakes.
3.
If you apply the brakes at the end of start/finish, rear grip will be vastly improved.
37 kg of lift compared to -41 kg of downforce !! This is a difference of almost 80 kg at
a moment when dynamic corner weights are often below 100 kg !!!
With such a wing rear wheels of a FWD now have a chance to take part of deceleration.
again: