I tried left-foot braking in both my cars (manual and semi-auto), and found I cant do it, and figured out why:
On both cars the brake pedal is set too high and too close to me and too far to the right so that I can keep my left foot on it without pressing it confortably.
Whenever I try to left foot brake either I get cramps on the left leg, or to be able to depress it, I must lift my heel from the floor, resulting in no feel for the pedal whatsoever. If I try to left foot brake with my heel on the floor, i can do it, BUT my foot is at an angle of nearly 60degrees... it hurts like hell. (note - when your standing your feet at 90º from your leg - bend your knees and that angle diminishes)
With gaming pedals, no problem with left foot braking at all. Indeed, after a long stint driving the to s-s or the GTRs, If I switch to the slower manual gearbox cars, I try to brake using the clutch, making for some... interesting turn1s :schwitz
I use the clutch pedal as a brake pedal on the SS and the Big GTRs)
Note2: Semi-auto: Clutchless manual gearbox, with a actuator-activated auto clutch. requires sequential style "up and down" shifts.