I think that this would be hard to tell, at least without doing a flight (and who can afford that).
I have had several different 25's and yes there were probably slight differences, but the over all character and experience was very much the same.
I don't know if they even mix up a new batch every year anymore. Even changing the packaging does not have to mean new beverage in it.
I do think that the variations in the 25's are less than the variations that I have experienced with the 18yo's.
Good luck, buy a bunch, and let us know..