Perfectly fine on a couple of flights within Mexico about a year ago. However, our bags didn't make it from Mexicana to our connecting AA flight in Mexico City, even though it was far from a tight connection. (Fortunately, this was on our way home.) No way of knowing who was at fault and I don't know if this is typical or just a random thing that could have happened as easily north of the border, but a data point FYI.