I can't recall a floating/IPO of the loyalty program unit being done by any North American carrier beside AC -- not to say that there has never been another spin-off in the North American market.
The spinoff has been a mixed bag, but one area where it was successful, was in the provisioning of 'saver' awards. AE insisted on a certain # of seats being allocated to award tickets for each route per cabin per month, which AC is contractually required to provide.