I am far from a fan of AF, but I regularly travel between ATL to JNB and will do almost anything to avoid the direct SAA flight. Service on SAA is often poor (I won't bore you with myriad stories) and the stopover at Cape Verde is pretty unbearable. Granted, the SA-CDG-US flight is going to be 3 hours longer in total, but I personally appreciate the ability to walk around an airport for a few hours. As an added bonus, you'll get more MQM on the route via CDG (though that wouldn't be a major concern for me).