To close the loop: I called DL and got a cranky agent on the Gold line. However, I was able to persuade her to switch me to a CDG-DTW-XXX flight with a similar connection time (less apprehensive of the connection time at DTW, and if I miss it, the next flight to my final is in 1:45, vs. 3 hrs if I went with the ATL option). Also, I'm happily back on AF metal to cross the pond.
As a bonus, I was refunded the difference in fare between CDG-ATL-XXX and CDG-DTW-XXX, which I wasn't expecting. This almost makes up for the flight going on sale three days after I booked it.
Maybe I'm being naive, but I never understand why posters X-out their city pairs...
Short answer: personal preference.
Long answer: FT is a great site for community, but I'd rather not participate to the extent of those who happily disclose full name, profession, location, their dog's middle name, and the place down the block where they shoot hoops. Not that there's anything wrong with that. I'd just prefer to not disclose dates, flight times, and where I'm headed.