There are some discussion before.
One big drawback is no tier bonus for even top tier members.
AA EXP(OW Emerald) earn 100%(?) bonus for your flight.
Unfortunately, CX Marco Polo does not provide this type of bonus.
From some point of view, guarantee seat service for Diamond/Gold member
is great. this benefit is applicable for even discount economy class
(Booking class B/H/K/L/M/V) of CX flight.