Moondog-
It seems I have backed into being your yogi on DCC. And as Yogi said "When you come to a fork in the road.............".
Two cases of DCC (or DCC-like) I'll relate. The first was in Paris about 4 years ago at a small bistro. It was a young relative's birthday and they treated us like royalty-including our dog. I got the DCC charge slip, and for the $3-$4 difference, I let it slide. I really think that bistro owner just got a better card rate from a slick salesman, and, anyway, I took it out of the tip.
The second case was Hertz in Italy last year. I booked in Euros, told the desk agent I wanted to be billed in Euros, wrote "Bill in Euros" on the rental agreement, but they still ran it through the DCC. I had a weeks' long email exchange with Hertz corporate, and they even asked Hertz Italy for a copy of the paperwork. Only when they didn't get a response did they give me a credit for a little more than what the DCC mark-up was. I don't know if I was an exception to standard practice-I think they claim that you have a choice, and if that is so in practice, that's how things should be.
Onward soldiers, onward................