Going through with a charge back is time consuming and requires back and forth with bank explaining what this is all about, declining courtesy credit, etc etc.

I was successful having Chase go through with the charge back for Greyhound Cafe where the merchant ultimately re-ran the transaction in local currency, but honestly, it took 2-3 month of my time.

I am in agreement with you regarding the principle aspect of it. Just wished it was easier.

It'd be good to have a list to reference as to who DCC and who doesn't. I used my CSP because this merchant didn't take a local HKD Amex.