This is definitely true. I have, on several occasions, tested the exchange rates by making simultaneous identical foreign currency transactions on MBNA AMEX, MBNA MC, and Capitalone VISA. The converted dollar amounts of MC and VISA always come out identical; the converted AMEX amount can be as much as 4% higher (but not always).

Now that MBNA is charging the 3% surcharge on all MC/VISA transactions I see no other solution than Capitalone. There is also USAA and a Pentagon credit union that offer 1% surcharge, together with an offsetting 1% rebate, but these organizations have restrictive affiliation criteria.

For ATM withdrawals, there is BOFI (Bank of Internet). They offer a certain level of refunds of ATM fees (both foreign and domestic), no foreign exchange surcharge, and relatively high interest (around 3.5% for checking). The drawback: daily withdrawals are limited to $US 300, no matter how much money there is in the account. Still, BOFI is good enough for getting small cash while traveling without paying outlandish fees.