You've struck a brilliant chord Dr. Whilps! Just as each tree is an individual member of it's species so is each barrel. When filled with American corn whiskey and laid to rest for years as the whiskey becomes bourbon things do change, albeit slowly. The mashbill; the yeast, the barrel, and the rickhouse all start off as more or less equal partners in a mystical process.
At what time does the barrel become the over-riding factor? This varies of course, but how old is too old? Older may be better for some barrels or some mashbills. You've all seen the commerical with the 50-something woman saying "I'm not getting older. I'm getting better!" Oh yeah well prove it granny!
Whenever I see pricey bourbons older than 15 years I am always leary that it's just another wrinkled up old lady that used to be a looker.
Have Shotglass. Will Travel.