If it is possible to choose a lengthier connection time that would be better. If all goes smoothly a 50 minute connection time is no problem. However, if your plane is slightly delayed, you have a big terminal connection (which you likely won't know until you get there), or, as others have noted, have issues that would slow you down, I would say it would be easy to miss your flight. Delta is notorious for giving ridiculous connection times, so I would not rely on the airline to make a wise decision here. I have seen suggestions for flights with 35 minute connection times in Atlanta! If you miss your connection they will likely put you on the next flight out available for your party, but who wants to deal with that? Personally, I'd opt for a longer connection time if feasible to make life less stressful.