Join Date: Jan 2011
Location: Philadelphia, PA
Programs: AAdvantage Exec Platinum, Hertz #1 Club Gold Five Star, IHG Platinum, Marriott Gold, HHonors Silver
Posts: 2,035
What would be your plan if there is a delay/missed connection somewhere and they end up sending on a different routing to CUN (i.e. HKG-LAX-DFW-CUN or HKD-LAX-PHL-CUN)? There is no guarantee to get to MIA and the ticket you purchased is strictly for HKG-CUN.
As for short checking bags, typically I don't think AA does it, but they may for extended layovers like the one you are planning (others on here would have more definitive answers). However, even if the answer to this is Yes, you still assume some risk if things don't go right.