I open for discussion my questioning the concept of Upper Body/Lower Body separation as a two part thing with the pelvis being part of the upper body.
For example, at times I feel myself anticipating with my Upper Body while my hips (pelvis) are still square to my legs and thus my skis.
I have seen many still images of racers where their upper body is facing more downhill than their hips, so they are using separation at that point.
Rather than going into more detail, I query why as there are two rotational hinge points are we coached to only use one of them?
(Hinge 1, femurs rotating in hip sockets. Hinge 2, core and upper body rotating above the waist.)