I've also seen left-foot braking with an automatic transmission advocated in print for street driving, as a way you can take an extra smidge off your reaction time in potential "kid runs into the street from out of nowhere" situations. The left foot is poised to react but isn't actually actuating the brake until that's needed. You have to train yourself to do it both smoothly and as near-reflexively as you would perform the usual method -- no hesitation and no indecision.
That having been said, I gave it a fair try lo these many years ago and gave it up, in large part because I was spending significant time with manual transmissions.
It isn't usually considered to be in the mainstream of ordinary driving techniques, but if you practice it and think about how to do it and aren't too uncoordinated with what for most people is the off side of your body, you can get it down pretty well.
I still use my left foot *after* having stopped to prevent rollbacks when I come to a stop sign or red light on a nontrivial upgrade (again, that's with automatics -- on manuals, I coordinate the handbrake and clutch).
