The debate about using downshifting in conjunction with the brakes or brakes alone has continued since racing began!
There is sound principal to be found on both sides of the issue.
For myself, having tried both ways in numerous cars, I prefer brakes alone for maximum slowing/stopping effect. I like to focus on brake modulation, braking right to the point of 'lock-up' without going over that point. Extremely difficult to do while heel/toe application is also happening. Braking alone is of course the quickest way to over heat your brakes, but I believe it is also the quickest way around the track. I use heel/toe only to get into the final selected gear at the last critical mili second. I may downshift through the gears while braking and even double clutch when I'm taking it easy to preserve the car.
Heal/Toe is primarily a way to rev the engine WHILE braking to keep 'soften' the impact of letting the clutch out in a lower gear. The engine wants to 'rev up' to match the new trans gear ratio to the speed of the tires, so rev the engine and THEN let off the gas just as the clutch re-engages while still braking hard. MUCH easier said than done! Heel/toe can also be used effectivly to double clutch, when done RIGHT it has the same impact as heel/toe alone, softens the impact of clutch re-engagement.
Once when my brakes FADED to the point of GONE, I slammed it into 2nd gear going WAY to fast to 'lockup' the rear as a method of braking. The rear end came around, threatening a spin, which I was ready for. I went into the corner sideways and came out looking like a 'pro' (but needing a change of underwear and worried about damaged 'parts' on the car)! Calculated risk, I figured it was better to break something than hit the wall.
In fact here is a picture of the corner and the car (taken on a different day). Note the extreme angle of the front wheels, I was 'drifting' that day on purpose.
