Well, my humble opinion is this: Given that the original flavour is quite different than the "finish" cask you will taste it more. However, they can't be too far apart. I agree that the Ardbeg on rum wood is easy to taste and a reason for that might be that smoke actually adds a little sweetness - especially on the nose (try to recall a bonfire with wet wood).
That said I feel that the better wood finishes I've tasted are the ones that enhance a flavour that might not be the most obvious one in the original whisky. For example Ardbeg+rum, Caol Ila + cognac (enhances the pear and citrus) Springbank + rum (enhances the dried fruit on the nose and palate)
Then again I might just be too academic about this - how about I just shut up and drink?