Arbitorn, those listeners that are doubling Warm 98's share are already listening to radio. They just abandon their regular station for a month and a half. Had there been a huge migration of people to radio for Christmas music, as you theorize, then there would have been a cume spike for the market. That didn't happen, and in fact, cume for the Holiday book is lower than the yearly average. Looking at AQH cume, you can see that when Warm 98 went back to its regular format, several stations had double digit percentage increases in their AQH cume, while Warm lost more than half of theirs. Stations that came back strong were WGRR, WREW, WOFX, and WUBE. WAKW saw the same pattern, with WNLT increasing by almost half after WAKW goes back to regular format.
So, in summary, the listeners are already there and they are getting what they want for ten and a half months of the year somewhere else.