I just tried entering the first 4 digits of my AMEX, and presto, the fine print appeared on the payment page. But there's still no mention that there's an additional 3% fee, although it sure appears that it's being charged.
On yahoo today's USD to EUR exchange rate is 1 USD = 0.9389 EUR
When I had my account selected to EUR, the total charge for my test dates was 541 EUR. When I entered the first 4 digits of my cc, this language appeared under that total:
"You are paying in USD. Your total charge is $592. The adjusted exchange rate for booking this listing is $1 USD to €0.9143 EUR."
And when I selected USD for my currency, the total charge was 592 USD, and this language appeared after entering the first four digits of my cc:
"The adjusted exchange rate for booking this listing is $1 USD to €0.9143"
Arrggghh