[quintinsykes]

You're absolutely right, the structure is different for Signature and PIN debit. Pre-Durbin there was a large gap between Signature and PIN debit interchange income and banks wanted you to use Signature debit for that reason.

With Durbin rules implemented that gap has narrowed and now the bank wants you to use an actual Credit Card vs. a Signature Debit transaction because they will make more interchange income off of it.