Originally Posted by
touristtrap
I might be wrong but I don't think one can use Amex at GC.com if not grandfathered.
I haven't tried at GCM.
On the other hand I used to purchase VGC with AGC at WM and they would auto-drain.
Just last week i made a purchase on giftcards.com using SPG Amex for the first time. No issues.