I was just did SCL-DFW in J on the 772 in 8H and it was totally fine. I originally booked the 763 via MIA because service tends to be better in J on a 2 class plane versus 3 class in my experience but the DFW based crew on my flight was great in J.

I don't really have issues with the angled lie flats on AA and actually find DLs lie flats to be like coffins with so little room at your feet.

I've had hit or miss service too going through Miami to Deep South America but the DFW crews are usually always great from my recent flights.