jwolthuis - 4:56 pm on Feb 3, 2012 (gmt 0)

my amex customers spend on average 20% more than the other three.

It's only if there are no alternatives available will I whip out the Visa.

I agree. We don't accept AmEx because of what Planet13 said, and I think we're money-ahead.

AmEx cardholders always have a backup Visa card to use to place those 20% bigger orders, and they don't reduce the size of their shopping cart when they pay with their backup Visa.