Guys, why argue about needing to discard anything learned in skiing? A skilled skier can readily switch from one learned system to the other without carrying one set of skill into the other.
In my sixty plus years of skiing and over three decades of instructing in three systems, I can ski pure old French down-unweighting, pure Austrian counter rotation-as-turning force, American Ski Technique and even the very old Arlberg technique of turn initiation by sinking while counter rotating to wind up then an sharp up-unweighting with a powerful body rotation yanking the skis around, and I don't need to have 220 cm skis to do it, I can do all of the above on my shaped skis. And I am not alone, skilled skiers everywhere can do that.
Now to PMTS, it is really a very easy system to learn, designed so by Harald in order to grasp it just by reading the books and seeing the videos and practicing what's prescribed. He breaks down skiing into primary movements and refinements thereafter. I can do it, my cousin Franz can do it as can Fritz. We play with it and really find it a relaxing way to ski, especially for us older folks.
Not once does rotating, wind up or unweighting come into play just because we are not skiing that 'other' system at the time. Maybe it is harder for skiers who haven't grown up in the mountains and skied since early childhood, I can understand that when you don't start skiing until you are 25 that you are ten years behind everyone who started early. 90+% of skiers you see on the hill are self taught and have acquired habits which are hard to discard, but they never could ski right in the first place.
Are you going to tell me that the PMTS certified instructors who in their day job ski and teach ski school prescribed maneuvers most likely influenced by PSIA four hours a day cannot switch totally to PMTS when teaching a lesson in that system? Just ask Arcmeister.
I don't think that arguments to that point are very useful.
....Ott