Some more experience with AeroMexico & complimentary upgrades: had 6 flights with them (AMS-MEX-ACA, MEX-CUN-MEX, ACA-MEX-AMS).
Asked about complimentary upgrades to business at AMS, gate agent said I am eligible but there are no seats available. Asked again at MEX going to CUN, lady said I was eligible but she couldn't add me to the upgrade standby list as the system only allows AeroMexico and Delta FFs. Asked once again at CUN going to MEX and then MEX going to AMS, both times was told the upgrades were only available for AeroMexico members.
On all 6 flights I got free AM+ seats and whenever I asked at the gate and there was a free seat, they sat my zero-status friend next to me for free too.
Overall they seem like a nice airline
