It really does pay to do your homework. I've so far used all mine purely for flights as you still earn points and status as compared to some hotels where you don't get points and benefits if not booking direct. Just booked flight last week and direct was $1269 whereas through Amex was $1090 so it was cheaper again.
FWIW, whenever I call up, I use Platinum travel and they previously told me they use GDS and are a different company to the Amex Travel website. As my Explorer is linked to the Charge, I've been able to use both credits through Platinum travel but I had to use the Reserve credit through the website as that credit doesn't show up in the Charge account so I assume they can't see / use it.
FWIW, whenever I call up, I use Platinum travel and they previously told me they use GDS and are a different company to the Amex Travel website. As my Explorer is linked to the Charge, I've been able to use both credits through Platinum travel but I had to use the Reserve credit through the website as that credit doesn't show up in the Charge account so I assume they can't see / use it.