Great vid on your set up.
It is easy to get caught up in the confusion, but the 'Heel-Toe' technique is just as its spelled out. The heel-makes the first strike, not the toe. Its not called toe-heel, or toe toe.
Heel making the first strike is not an easy technique to get b/c as drummers we're hard wired to make a toe stroke, we're so used to making the first hit with the front of the foot. With heel-toe proper you lead with your heel, not your toe. Heel toe is a useable stroke for doubles, there's great power in the heel.
If you hang your feet off the back of the foot board, you're not doing heel-toe proper, you're dropping your heel to accentuate a second toe strike, a different stroke definition all together, don't know why one would call that heel-toe, 'drop heel', make up any name that fits, but 'heel toe' is the heel striking the pedal board first.
This is what every metal band doing "HEEL TOE" do. you don't see any drummers doing 240-300bpm slamming their heel into the pedals. . I understand what your saying but I think your getting to caught up in terminology. (also there is no arch of foot-toe technique)
Using your heel will work for a double stroke, but I wouldn't want to use it for blazing fast 16th notes for an extended period of time. if you watch or listen to any extreme death metal you will see this is the technique used, and it is referred to as heel toe. I didn't make it up. Search Youtube and you will see.
Either way, this technique works and is easy to learn. It is fast, consistent and conserves energy. It is the same motion and essentially your heel is making the first stroke, it just isn't hitting the pedal board. I can do it with my feet up striking my heel into the pedal, it just doesn't seem as efficient. I have also heard of guys injuring their heel doing it that way, and it doesn't work on shortboard pedals.
and FYI, my first hit is with the heel, the second hit is with the toe. I am not using my heel for the second hit.