Wanted to add a data point from a recent trip, of course YMMV.
Arrived in MEX around 10pm on a Friday evening. Was able to use the e-gates with a US passport and did not wait at all. Heard some mixed things about when to arrive at MEX for the return flight but the consensus seemed to be 3 hours with luggage 2 hours without. Left Polanco at 330am this morning for a 6am flight, rolled into departures at 355am. Did not have any bags to check but there was no wait at security, and we were airside at the AA lounge at 405am (and it did not open till 415am). Overall, a very pleasant experience compared to my experiences at CUN.