hello--

Planning a trip to Mexico. I can either book directly on Mexicana (cheaper) or I can book via AA as an AA codeshare on the same flights. I'm PLAT on AA.

Is there any difference in terms of mileage accrual, mileage bonuses, lounge access, premium check-in, or anything else that would make me want to book it as an AA codeshare rather than as a mexicana ticket (other than the 125 mile online booking bonus)? Finally, I know Mexicana often offers gate upgrades-- am I right that the ability to receive these upgrades is NOT related to whether or not my ticket is booked as an AA or Mexicana flight?

thanks.