Yeah, I've been doing it with palm down since the 70's.
I was at a clinic with Lenny Krazleburgh (sp) about a month ago and he showed us that exact thing.
He had us finish the pull with the palm facing toward the thigh. This keeps the hand from going outside the "body cone". The idea is to have the body as compact as possible without disturbing the surrounding water. Also, when you think about it, if your hand is pressing down towards the bottom, your body is responding upwardly and why would you want that.
I seem to remember a David Marsh and Kim Brackin video saying the same thing.