I usually book around 45 minutes for international to domestic in ATL.... (mind you I fly standby and don't pay for tickets, otherwise I probably wouldn't do that)
With that being said, I make around 75% of those connections.
Maybe I get lucky, but I'm normally through customs and TSA in a breeze in ATL. Good timing maybe.
I say why change it, if you can make it, which you probably will, you'll get home earlier. If not, DL won't charge to put you on the next available flight.