Originally Posted by
Majuki
We had some informal discussion about it on this thread about a year ago. There was no rigor around our experiment other than transactions using AmEx in a similar time period/posting date than Visa/MC seemed to use a slightly more unfavorable rate. All of these data points were within the margin of error of ±1% and all were much better than any DCC offered.
About a year ago there were hardly any 0% FTF Amex cards, so I guess data points would have been thin on the ground. ±1% is huge, when we're talking about MC being at the mid-rate, Visa being 0.4% (2014) to 0.7% (2015) above and Amex being somewhere between MC and Visa.