I'm rooting for ATL all the way(2nd fave team) but, I think the Whiners will win and I"ll root for them in the SB for a number of reasons, including many of those listed in the OP.
Personally, my dad grew up in Santa Clara and I was born there as well, and grew up loving the Hawks and the Niners(Joe Montana, Jerry Rice) and HATING the Raiders(old AFC west).
I can never root for Tom Brady to win any game ever, unless it immediately helps the Hawks...and even after then, I need a shower. So I'm rooting for Ray "I killed a guy" Lewis, but I expect the Chowderheads to win that game and play the Niners in the SB. Gotta go with the Whiners for divisional dominance, and their impending decline.
Their 1, will pale in comparison to the 3 or 4 we're going to win over the next decade.