Um, I still believe that you should always double immediately when your opponent is 1 away. There is no disadvantage to higher stakes, and your opponent does not get the advantage of holding the cube.

For example if you trail 6-4 up to 7, and you don't double. You can wait until you get into a position where you threaten gammon so much that your opponent will drop and you get to play the next game for the match, however had you doubled early you would be playing for a gammon to win the match!

It's possible that your opening roll is so good that your opponent would pass (for example you roll 3-1 and your opponent rolls 2-1). Now you may be too good to double if the score is 6-5 since you will erase your chance of a gammon.