Arch,
Shoulders follow the hands in my motion. The right wrist is bent to a MAX by shaft-parallel-to plane line position, which gives me an arched left wrist. Homer mentions the "disruptive" shoulder takeaway, but I can't find the exact place at the moment. Take another look at Brian's article, "Never Slice Again", and check the 2nd photo. I TRY to retain that max bend into the follow through. I'm very flexible, and the max bend for me is about gives at most a 45 deg angle between the shaft and the right forearm. The thing I like about max bend is that an extreme is easier to consistently execute than something in between, AND it requires less shoulder turn to get enough "deep" enough on the backswing.