At the AC in ATL now, after easily grabbing and rechecking my luggage with plenty of time to spare. Thanks to all for the info and tips.

Security was indeed pretty slow (relative to what I'm used to flying out of MSY or DCA) this afternoon, about 15-20 minutes for Precheck. Might have been able to hop in the premium line for a slightly shorter wait but I wasn't in a huge rush. As an additional aside, AA baggage handling today at ATL was fantastic. 10 minutes from bag offloading (per AA online bag tracker) to carousel, and all of the bags that came off first were priority tagged. Perhaps this was just a smooth day, but the apprehension I had about this connection seems to have been not so warranted.