Evening flights in and out of ATL in the summer are always a risk. Summer afternoon/evening thunderstorms are common and has thrown Delta flights into disarray a few times this week already. I'd probably just take the overnight connection, but if you're in a premium cabin and are quick off the plane you shouldn't have much trouble with immigration. I just took this flight last month in F and immigration didn't take long at all (I do have GE though). Bags took about 15-20 minutes though. After collecting bags you'll have another 15-20 minute journey via walking and plane train to the domestic terminals.