Mark, check out when you can the 100 proof. The make-up of each (80,86, 90, 100 assuming the latter two are still made) is not necessarily identical, e.g., the 100 contains older whiskey than the others or some of them (I was told this by someone close to the distillery). The 90 is usually fine and the others can be too if their balance is right, each bottle is slightly different.
Gary



