A co-worker was asking me to post this question for him, what are the upgrade chances for the YYZ <-> CUN flights as an E50K at T-5. He will be travelling with his wife that has no status. I told him that my concern is that if R=0 at T-5, the chance to get both upgrade might be low at the gate.
May not be too bad in my experience unless you have people who upgraded as part of an ACV package. Usually leisure travellers on this flight. You may want to confirm what sort of fare he has an ACV fares are only upgradeable by higher tiers.
Also, as I mentioned in another thread, you may want to confirm that there is indeed J on the aircraft.
Good luck!