I agree with you, Kathryn, I think she puts it in front for plies to hit the specific muscle better. However, she often tells us to pick whatever position suits us, so it must not matter that much. Personally I put it in front if the weightload is lighter, but for the heavier workouts it goes behind my neck, as my shoulders get tired from supporting the heavier barbell. She also uses one 40 pound dumbell for plie squats in the SH series, but I use a barbell for that because I like to go heavier, and holding such a large dumbell tires out my shoulders and forearms too much.
Sandra