I did this 2 weeks ago-ORD then SAT. Arrived about 3 hours before flight. There was 1 desk with 2 counters open. There was a small queue. Was unable to check in on line in either direction as they said my documents had to be checked at the airport (UK passport with esta).
My luggage certainly did not the disappear onto a belt! I have a large eastpak wheeled soft bag- they said that all soft bags had to be taken by the passenger to another belt. I questioned this and was told it was standard manchester practice. You had to upload them yourself whilst 2 guys on the desk/belt watched. The belt was quite high and it was a definite lift not a pull/push. I also ended up lifting the bag of the old chap behind me. I was very non plussed that they just watched while travellers clearly struggled and based on this alone I won't be flying with AA from Manchester again.