We use ATL 9 times out of 10 when we travel just about anywhere. We have Mobile Passport and 'usually' do carry-on only. Still, I would not attempt a 90-minute connection in ATL, or anything under 3 hours, for that matter. As others have stated, it's a LONG hike to luggage pickup and customs (no train access). Also correct is that there is no Pre-Check when returning back to the States, weird as it may seem.