I'd add my 2 cents on this discussion..
I've had about 50 runs or so on my new coiler SLC (first board) and have made adjustments to my cateks about every 3rd run or so and have made the following observations (predominantly using crossunders with shoulders squared to the nose):
board carves sharply when put up on an edge so that in order to ease up on the quick turns, I had to shift the board (under my body) to a more forward position while coming into the apex just to keep control of the arc. This resulted in rear leg burn and some serious instability out of the apex (most noticeable toeside). Just shifting the board from edge to edge resulted in some really quick, ie: see-ya-later, carves. This was with the bindings in the center position, both fr/rear.
I began shifting the bindings back the smallest amount each time and realized that I could adopt a more neutral stance, use higher binding angles and use the board's position under me more effectively. This applied to heelside or toeside turns. Now I am acutely aware of my body's position as it relates to the board and can gradually drop the board underneath me to reach the desired apex. When apex is reached, I can unload the nose with more control and have it accelerate underneath me to it's forward position to begin to intiate the next arc. Now, I haven't been video'd, but if feels like my knee's stay open, hips / shoulders keep aligned and I have a solid platform throughout the carve.
I've also cured the "knees together" issue by raising the (front side) heel on my back foot since I was tucking my back knee in behind the front to apply pressure to the heelside edge.
I've got to move them back another 1/4 inch then I think I'm good to go for the slopes I'm running. I suspect that the steeper the pitch, the more forward the bindings need to be.