So, I'm no speedracer, but have been to the track a lot and been in numerous schools (Skippy, Porsche Driving Experience, etc).
I was driving with a friend of mine and he stated that I was doing heel toe wrong. The way I do it is to overrev and then to shift in the proper gear as the RPM's fall. For instance, say I'm in 4th, I'll brake, put in the clutch, blip the throttle to say 6K, and as it falls to 4K put it in 3rd.
My buddy says that you should match the blip precisely and slip it in gear. So, in 4th, blip to 4K, and slip it in.
Funny, I've driven with a lot of instructors and nobody ever mentioned my heel toe technique as being wrong (even drove with Hurley Haywood once!).
Does it matter? It seems that his method is probably better, but seems so much harder