I just (over the weekend) had a schedule change on a TATL PS mileage ticket that I wanted to upgrade with GUCs. The return already had confirmed upgrades and now the connection violates MCT. DL rebooked me (still all their metal) through another hub with confirmed upgrades, but it required an earlier departure (by a bit over two hours) and a TATL D1 segment with a horrid 2-2-2 configuration. I called today and got an extremely competent agent on the "Diamond line" right away. I had already investigated what happened and what I wanted and everything was done quickly with no argument or pushback. I asked to be put back onto the original TATL flight in D1 (upgrade space was available) and to take the rescheduled connecting flight in domestic FC the following day, (of course in FC) which created a "connection" over 24 hours (and of course a nice sleep in an airport hotel at my expense). No problem and I didn't have to revert to my second choice, which would have been an earlier domestic connecting flight and less sleep or possibly a compromise additional connection at CVG since I didn't want to do any very tight connections. It was an even exchange.

During the call, I also pointed out that D! upgrade space was available on the outbound. The agent confirmed my upgrade very quickly and of course upgraded the domestic connecting flight from C+ to FC.

This seemed like a return to the DL service that remember from before the pandemic, although I sense that there are fewer choices for the domestic connecting flights as well as fewer domestic nonstops to/from MSP. I wish I could have given the agent a 10 rating instead of just 5.