Great article Brian. I personally prefer a very slight cup in my left wrist at the top, but I love your impact position. If everyone can get to your impact position, golf intructors are going to go out of business ...
Have you heard of a training aid called "Swingyde"?
www.swingyde.com.au
Someone (goes by the name of dognut) on the Single Axis forum has suggested an alternative way of using the Swingyde that may help to feel the idea that you are portraying in your article. Here's an exerpt from a post of mine illustrating his ideas.
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I have drawn a couple of diagrams to make it clearer. Dognut may want to add or correct anything that may be different to his way of doing it.
Install the Swingyde upside down so that it fits onto the butt end of the club. Here is a diagram.
http://www.network54.com/Realm/tmp/1068420338.JPG
The Swingyde should be rotated 15 to 30 degrees clockwise from the leading edge so that if you looked down the shaft from the butt end of the club, it would look something like this:
http://www.network54.com/Realm/tmp/1068420467.JPG
You'll find that the butt end of the grip is a bit too thick for the Swingyde. You won't be able to put the nut and bolt on. Just use a piece of string or one of those cables with teeth on it to secure the Swingyde.
Start with some gentle half to three quarter shots. Take the club back until the hands are around chest/shoulder height. The Swingyde should be barely touching the inside of the left forearm where the wrist watch band is. (BTW, you may want to wear the sweat band that came with the Swingyde over the wrist watch).
Now swing slowly down to the impact position and feel the pressure of the Swingyde on the inside of the left forearm INCREASING. Do whatever the hands need to do to feel this increase in pressure. If you look in the mirror, you'll notice that the back of the left wrist is becoming BOWED. (See picture of Hogan's raised wristbone in his book "Five Lessons" page 102)
Now swing gently through to the mirror shoulder high position on the followthrough. The pressure should have eased off somewhat, but the Swingyde should still touch the inside of the left forearm. You'll notice that the back of the left wrist may be slightly cupped but is still relatively flat. The palm of the left hand should now look somewhat towards the sky (i.e. the left forearm supinated and the left hand turned over).
When you are comfortable with this, try hitting some gentle 9 iron shots, feeling the same solid hand action through impact. You'll find that the contact is crisp.
Just to finish off, let me add that I think dognut's way of using the Swingyde is better than any other training aid or method that teaches you to keep the left wrist flat through impact. The tactile feedback from the Swingyde and the fact that you have to use the correct muscle action in order to achieve the pressure from the SG on the left forearm makes this ideal for learning. No verbal thoughts. Just feel the pressure and observe what you have to do.
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If you have a Swingyde, try it and see what you think.
Cheers,
Jono.