Have to comment on the Diners acceptance in Canada.
I have a Finnish DC, card number 36xx etc. I have spent quite some time in Toronto now and I have completely given up on trying to use my DC anywhere. My experience is that it is only places who clearly state that they accept Diners who accept Diners. The MasterCard thing is useless. I have tried several times to use the card in places where MasterCard is accepted, but not Diners, and told them that it should be accepted, and asked them to try. Most get insulted since "they know" it's not accepted, some restaurants even claim they tried to swipe the card and it didn't work. Now with the new Discover-logo, most say that they don't accept Discover nor Diners...
Thank god I have my Visa and nowadays also carry cash with me.
Thinking of going back to Amex after 5 years with DC, especially if the SK/Amex partnership brings something remotely useful. It might not be accepted everywhere, but at least an Amex is an Amex, period.