If you want evidence of Savannah voters NOT simply opting for candidates of their own race, take a look at the aldermen-at-large positions.
Carol Bell, a black candidate, won Post 1 easily, with 64% of the vote in a 3-way race.
The lone black candidate in the Post 2 race, Clinton Young, picked up just 29% of the vote. While that was enough to get him into a runoff with former state representative Tom Bordeaux, Bordeaux would seem to be a shoe-in since he only needs to pick up 1/3 of the vote that went to Bill Gillespie, who finished a very close third.
So the Post 1 contest saw a sizable number of white voter go with Bell, and the Post 2 race saw at least as many black voters choose Bordeaux or Gillespie. Take a look at the numbers: