Wow. How did I miss this thread? Turbo, I don't know if you have ever actually driven your car on a track, but I'll try and explain things.

First off, the syncros in every modern manual transmission eliminate the need to double clutch. The purpose of double clutching, as you noted, is to get the tranny gears spinning the same speed as the engine to help engagment and reduce wear. Modern technology has removed the need for this though. If you want to doble clutch, go ahead, have fun. You're doing nothing but saving your syncros from doing their job.

Secondly, Heel and Toe shifting does play a part in weight transfer, but more from a smoothness standpoint than anything else. Most of the weight transfer approaching a corner comes from the application of the brakes. As you need to downshift you have two options while you're stomping on the brakes - 1)right foot on the brake, push in the clutch, change gears, and let the clutch out or 2)right toe on the brake, push in the clutch, change gears, rev-match using the right heel, and then let the clutch out.

Option 1 will get you jerky drivetrain re-engagment which will upset the balance of the car, by allowing the engine and transmission to slow down and then be "jumped" back up to speed. This will put even more weight bias on the front of the car (since you've probably not finished braking by now). Notice you don't need to double clutch here unless you are driving a car with no syncros, it's wasted motion.

Option 2 will allow for the smooth re-engagment of the driveline, allowing the car to remain balanced and predictable.

I have spent loads (over 10 years) of time on real racetracks racing both cars and motorcycles, and the concept is the same for both. Heel and Toe allows for smoothness and smoothness equals speed. That's all.

I'd bet that if you've never Heel and Toe shifted on a track, at speed, you'd probably be amazed at how bad you really are at it. I know I was. Practicing on the street helps, but cannot prepare you for going from 5th to 3rd at 120+mph on a track. You posted some good links, and it seems like you read a lot. Maybe you should go try it out for yourself.

Greg

'19 Genesis G70 3.3t AWD
'88 Chrysler Conquest TSI