I like the relativity reference you describe, but in reality the CM is almost always pushed up at transition during a traditional cross-over. So relative to the terrain, that smooth downhill motion of the CM is much more difficult to achieve with traditional cross-over.
vail snopro: Allowing yourself to give in to the forces of the previous turn just a little sooner, anticipating WHEN to release the CM /core from one turn to the next should resolve this issue in your skiing!
Indeed this seems to be the key to a smooth transition, but I believe cross-under turns make it much easier to achieve this. Racers do it all the time in SL where keeping the CM going smooth is probably the most critical.