Amex credit cards are not that widely accepted I do actually have an Amex merchant account but I try every which way but Mondays NOT to accept it if I can, reason being it charges the merchant (ME) the highest percentage rate to be able to charge your card as much as 5.5% plus then make me wait up to 14 days to get my money.
A lot of merchants try to pass this 5% along to the cardholder which is contrary to the Merchants contract and they could actually lose there merchant account if a customer complained to Amex mastercard or visa.
The surcharge is widely practised here so travellers checks are a great option and a set exchange rate of $2 belize to 1 U.S
All the best
Gaz Cooper;s DIVE BELIZE www.divebelize.com