I'm a US citizen with Global Entry arriving into the South terminal from YYJ on DL, with no checked luggage, then departing out of a South gate to ATL, also on DL. Am I understanding this thread correctly that I will clear immigration, then customs with my carry-on bag, then can proceed to my gate (with no need for the train since I'm still in the South terminal, right?). Will I need to clear TSA again?

Thanks!