I definately noticed the difference between the Balcones whiskey and the rum. There was also a slight char character from the beer aged on Jack Daniels that I did not get with the Balcones whiskey. I think over time the flavors of the different spirits would blend since the wood will absorb some flavors from them all but since there is also liquor in there that is not absorbed by the wood and get mixed in with the beer I get the distinct flavor of the liquor in my final beer.
Brewing since 1989 - BJCP National Rank
Fermenting: McChouffe clone, Samiclaus clone
Conditioning: Belgian Tripel, Barrel Aged Baltic Porter - in sherry barrel, Belgain Easter Ale
On tap: CAP, Dortmunder Export, IIPA, Dubbel Chocolate Stout, Wee Heavy, Whiskey barrel aged Wee Heavy, Baltic Porter