Oh sorry, the Amex Canada website mentions it still, i.e.:

* $300 USD per stateroom shipboard credit
* Exclusive cocktail reception with the ship's captain and/or officers
* Exclusive embarkation (and early embarkation, subject to availability)

Got our credit promptly with no problem. That was it. We did get invited to the bridge for a special sailthrough in Rangiroa, but I doubt that was related to Amex status.

The early embarkation would have been nice, although I would have had to know about it, being off in a hotel a $30 cab ride away.