Read it on the following blog site: https://www.uscreditcardguide.com/am...ngrade_Options Don't know if it is completely true or not (hence why I hedged and said "my understanding" and "probably..."). But I don't remember seeing anyone who has posted or said they were able to downgrade their SPG Luxury card either.

I do believe I read another site that discussed some of the "fine print" in the card T&Cs and there was verbiage around possible penalties if someone cancels their card within 12 months of opening it. So no matter if they let you downgrade or not, I'd make sure to understand exactly what the ramifications might be for closing/downgrading it within 12 months of opening or upgrading the card. (I think there may even be a thread here on FT concerning Amex's cancellation clauses.)