[zende]

This is dead on. Here's a few other things to keep in mind:

1. A Durbin Regulated Debit Card include any bank that has over $10B in deposits. That's most debits cards by volume.

2. We've been lucky in being able to negotiate with our processing banks (also called acquiring bank) to receive very favorable rates to pass on those savings. You have to factor in this cost in addition to the interchange defined by the card brands.

3. Amex is more expensive than most other cards, but Amex is also the only card brand that will negotiate on their interchange based on volume and other factors.

abalone: thanks for writing this up. It's a more detailed answer to https://news.ycombinator.com/item?id=7033534