Interesting to hear your views! Mine differ insofar as that I thought the Jameson 15yo/Millenium was quite similar to the Redbreast 12yo. In fact, I have to admit having severe difficulties separating them on the basis of the nose, alone. On the palate, the Millenium distinguished itself with displaying far more mature oak in a pleasant manner.
Lest there be any misunderstanding, I have to state clearly that I dig the Redbreast 15yo, as well. But maybe, just maybe, it had too much of that "in your face"-feeling to qualify as true Irish, in my view. The Millenium felt more like a logical extension to the RB 12yo.