Definitely
avoid Atlanta. In addition to the to-ing and fro-ing on the train, the ICE and TSA staff there are reputedly some of the most surly in the country.
(The only thing in its favour are airside smoking lounges
)
KLM gives a minimum Detroit connection time Int-Dom of 1hr 15m (cf. Atlanta 1hr 20m) and as noted above, if it's a single itinerary - no airline change - they'll rebook you FOC if your inbound is delayed.