At the RideSmart track day at TWS recently, Ty Howard and another guy (can't recall his name) were talking about weight shifting. They were adamant about two things in particular:
1. The hips (and thus, the shoulders) should be perpendicular to the bike. I've heard elsewhere about two styles of hanging off, this way, and another which involves essentially 'rotating' around the gas tank. Ty et al, really stressed the former, saying that the shoulders should be squared or (iirc) even facing the exit of the turn (I think this is the open-ness that Squeaky mentioned earlier).
2. The head should be where your inside-of-the-turn mirror would be.
They were not adamant about hanging off a whole lot, just getting one cheek off to the inside. They did make a point that by shifting the whole body to one side of the other, there's less need to hold on to the bars, allowing for better handling of mid-turn bumps and, of course, less unnecessary input to the bars during the turn.
I tried to practice all this, but didn't do so great, until maybe the last session.
fwiw.