My experience has been that these certificates are not really worth $300 that AMEX plat. charges you per year. One cannot save $300 with these. On the contrary, one cannot upgrade either. If I was to buy two tickets, I can upgrade myself as Plat. and companion using systemwide upgrades or N. American. Not with this certificate though!
So I ahve 'dumped' my plat. card and opted for a regular card. I would encourage others to do the same instead of paying a high fee when you only save about $125.