I did not read all of the previous posts, i dont have time right now but this is an intersting topic.
the hips slide to establish a pivot point, so if your weight is 50/50 at address you will bump back to establish the right femur as a pivot point
then on the downswing they will bump the other way to do the same thing
if they slide where they go outside edges of the foot you will be in trouble with swaying. the problem comes if you think slide the hips because this will not engage the lower part of the legs, the feet must be grounded and the resistance needs to start from there so it can work its way up all the ways to the shoulder

so in short the hips have to establish a pivot point, right femur, left femur, shift the weight down into the right foot, left foot and the slide and pivot should happen pretty automatically
my 02