gmw photos wrote: "If the vehicle dynamics system is doing it's thing to try to mitigate sway in just the truck, and ignoring the fact there is a trailer back there, how effective is the overall exercise ?"
My understanding is the truck does know there is a trailer back there, and it knows exactly what it is doing. The computer / mechanics of it were designed by uber-nerds, so I couldn't possibly understand how it all comes together. I did find a video about GMC sway control that I assume would be similar across the board.
http://www.youtube.com/watch?v=Bm_inXdTFsM