Colin,
I can certainly see the difference your 'tweak' has made and prefer it.
I have decided to go back to the tutorials over the weekend and learn more about sharpening so that rather than just using the excellent procedure that you provided as a guide which has given me what I consider acceptable results I need to understand more about the exact purpose of amount, radius and threshold adjustments. The information is all easily available to me, just a matter of concentrating and remembering it
One last question if I may, you mention 'roll it back everywhere except the centre' which I can understand the purpose of but what is used for doing this ? I'm only an Elements user and it is not something I have come across yet.
Grahame