[jaykay]

I have used it in the snow to give weight transfer to the front wheels to scrape down to the road surface and bite and reduce understeer before corner entry.....your foot comes of the brake at the apex like a clutch and throttle is applied to give you oversteer......rotating the car around the turn

In a front driver you can momentarily lock up the front wheels and nudge the gear lever into second for the down shift. I couldn't do this.

I have also used it to balance the car in long shallow sweeping turns to balance the car

The above is all loose surface stuff....maybe there are rally drivers on here who explain it better

I would think once you start driving a PDK left foot braking will be huge in bringing you deep and fast into a corner.....there is no clutch to push ....If we see brakes that work better after being "warmed" down a straight it will make even more sense.

On a track surface I don't think I would consider left braking unless I was using a semi auto box or was trying to balance the car where no down shifting was needed