One thing I must mention is that it's perfectly fine to practice heel-toe-downshifting whenever possible, including on the street. I got extremely comfortable doing both versions of downshift rev-matching above (with double clutching and without) long before I did a single track day or autocross event. None of those guys learned the technique just from going to those events.

While it's overkill for public roads (and sometimes scares the other ppl on the road) it's a pretty useful technique to have in case you decide to do HPDE's and whatnot later on.

Shingo

ps. If I'm not mistaken, I believe double-clutching when you're revmatching downshifts (versus revmatching while the clutch is still in) puts slightly less wear on the clutch for the sole reason that you aren't applying throttle when the clutch is in. Correct me if I'm wrong...