Wil: If you are 1 away from winning and your opponent is 2-away, you should drop any double when your chance of winning the current game is below 50%. The same is generally true in any case where your opponent is an even number of points away. If your opponent is an odd number of points away, then you should take any double unless you are seriously concerned about being gammoned.

Again, the percentages should be modified if you think you know you are better than your opponent or he is better than you.