I normally wait for others to post their thoughts, since I'm not good at thinking on my own, and when I do, I'm normally off.
Both would have high approval ratings. In the end, it would come down to the better of 2 good's. In real life, Al Gore was a horrible campaigner, and Nunn isn't like that. In 2000, it would have taken a pretty weak Democrat for Republicans to win. Republicans lucked out.
Nunn defeats McCain is a respectable fashion. I don't see this as being a "bloody battle".
Popular Vote:
McCain/Allen: 47.76%
Nunn/Dean: 50.29%
Electoral Vote:
McCain/Allen:213
Nunn/Dean: 325
Tossup States: West Virginia, Ohio, Florida, Missouri, Iowa, Wisconsin, Minnesota