Repeating a lot of what's been said but:
1. I don't think I've ever had a bad seat at the Cell (especially after the UD fix), and like others have said it has the best food in the Bigs. Plus, odds are you'll end up sitting next to a knowledgeable fan who you'll be able to talk baseball with during the game (you won't find that on the northside).
2. I agree that the diehards are probably even, but the casual fans choose Wrigley as a drinking hole and b/c they've done better lately. When the Sox are doing well, especially in the playoff years, the casual fans all shift to the South.
Welcome aboard