Comparing WXIA and the Falcons with PCH and the Braves is a different animal.
With WXIA, you're talking about a station renting HD equipment or hiring an HD truck to produce four games of preseason football. Less than a third of the NFL teams are doing preseason games in HD.
There was never any question that Peachtree TV was going to do the Braves games in HD. Don't know where you heard otherwise, but it was always going to happen for the home games. Turner already owned the equipment and had permanantly wired Turner field for HD when it was still under TBS. In addition, Fox had already announced that all of the FSN and SportSouth home games would be in HD. The only question was would cable and satellite providers pick up the HD feed. Comcast and Charter came thru big all over the southeast, putting the Peachtree games in HD in each of their markets.