Let's go back to why people were taught a stem christie turn. Think about the equipment in before the advent of modern side cut skis in the mid 90s. They were basically straight and would only go in straight lines unless they were were bent into a curve by loading them up. In those days only a very good skier could carve both skis.
So how do you as a beginner turn a straight ski from a parallel position? Easy, you push it out to the side, stem it up the hill or step it up the hill, so it is pointed in the direction you want to go. Then you step on it, transfer your weight from the downhill to uphill ski, to load it up and make it go. When you load it up you bent it slightly. Then you slid the inside ski into a parallel position. During the turn most of your weight is on the outside ski to help maintain the bend. This was the "old" way of teaching skiing. It evolved out of the necessities imposed upon us by the equipment of the time. This is how I was taught to ski in the mid 60s.
Parallel turns were taught first as a parallel uphill christie. Then you just changed it to a downhill christie and bingo you were parallel skiing. (Note: The classic definition of christie is a skidded turn. In the 60s it differentiated between a skidded parallel turn and a carved parallel turn. Now, however, christie means a wedge type turn.)
Fast forward to today. We have modern side cut shaped skis. What a difference! The ski can do a lot of the turning work for you. To keep up with the changes in equipment we have changed the way we teach. Why? Because it is easier and more efficient. We have been able to eliminate "negative" movements up the hill to initiate turns. Why? Because it is easier and more efficient. Why wedge? Because the wedge gives a balance platform. The outside ski is still turning as if the inside ski were parallel to it. In other words, the wedge turn is just a parallel turn with an inside the turn training wheel.
There you have it. Ski teaching has evolved to fit the evolution of the equipment. As it rightfully should. Do I teach stem turns? Absolutely. Surprised? No need to be. I teach them to help people change lines quickly, and initiate turns they might not otherwise make in crud, in bumps, on steeps. When do I teach it? After they have mastered modern movement patterns. Stem and step christies are an addition to the toolkit that skiers need to be more versatile in their skiing.
The only real difference between new shaped skis and old straight skis is the length. The sidecut really is not the issue. Only if you carve. But when you are wedging or learning basic parallel turns the sidecut is not what its all about. Its all about technique. Just the same way you back then needed to stem to turn you do need to do it today. We even took a step back. We dropped the stem and retarded back to the wedge. Now all our skiing really is wedging. Remember the woman on the magic carpet? The stem christie is a more advanced turn than the wedge christie.
Efficiency? Only good definition would be less tiring. Is the stem christie more tiring than a wedge christie?
Also, you say that you have dropped the stem because it was a "negative movement uphill" to initiate a turn. Still you make the exact same negative movement when you open up the wedge. And you think that is justified only becuase.... sorry, I cant think of any good excuse myself. Maybe its because its so small. A micro wedge? Ooops, I think that is a negative thing as well. Remember that a stem can be just as small as the wedge. The guy in the video did a good visual demo but that should not be misstaken for how to make a functional stem christie turn IMO.
But its interesting that you teach a stem. Yes, I too think that a versatile skier should be able to make a stem turn. Your training weel analogy is good. The wedge gives a very stable paltform.
this post is full of so much misinfo. but you dont seem to care at all. Sidecut matters alot in skidded and scarved turns. I have skis with sidecut from 12-40 meters and let me tell you the 40 meter skis suck to ski skidded turns on unless the snow is really soft. sidecut is not just about carving.
please can you just go away.......