Ta Vando - my stance has changed dramatically. The pic of me sailing upwind doesn't really do it justice (lots of short-sharp chop combined with a high boom) - my profile pic is much closer to what I now use. I reckon stance is probably about 80% of how the fast guys go fast, ie: maximise leverage, unload the fin, control the board trim, etc
What got me thinking originally was that there was a great pic of you sailing towards the camera, from Al's SF 2006 during a NW'er. The sail was twisting reallying well and board trim looked superb. After looking at lots of pics/vids, there were two main ideas that I ran with, a) higher boom with longer lines, b) straight'ish front leg and quite bent (chop absorbing) back leg.
Still have some way to go - I want to flatten out the board trim as I think this is the difference between the Mal's/Spotty/Daff's and the me's... So I think I have to commit some more weight to the front foot + mast.
One point that I think I am finding, which might relate to body weight (or lack of skill

), is that I find that a bit more sail twist than we see presented in the static pics of the Koncepts, results in a bit more speed (or at least better control) - not much more, maybe half a panel more - so that instead of the head twisting, the whole upper-body will twist.