Ott,
great post! Quite interesting to get some historical perspective on skiing and ski instruction!
Just a tidbit of info on your question on how PMTS handles the not-so-fits: I'm by no means an instructor, but I had the opportunity the past season to teach skiing to one of my son's friends, a quite overweight, non-athletic boy aged 10. He's not skied much before, maybe some 3-4 times, only wedging down the slopes. And with his overweight, and generally non-athletic situation, he ended up exhausted quite quickly using the wedge approach. Anyways, last season, I spent maybe 2x2h with him, teaching him PMTS (as far as I know it), and after those two days, he is able to ski, even black runs, a full day without getting exhausted, and he's enjoying it.
For sure, I got him onto modern skis & boots, before we started skiing, but I didn't do any alignment.
Cheers,
Tommy