Well, I don’t have any additional data either. I do remember that many of those races were razor-thin close, but nearly all of them broke the Democrats’ way.
As for how many 2006 Independents were Republicans in 2004, I don’t know. As you correctly point out, my handy dandy chart doesn’t give me that information.
Michael Barone is the Sarah Palin of political analysts. :)
See #112 as to my take on ‘06 and the difference this year, FWIW.