I had no idea there were so many threads on this topic until seeing your posts in my inbox.

To be fair, I haven't used Discover in a while, but the Discover/UP relationship is supposed to be universal, as far as I know. Just out of curiosity, how good is your Chinese, and how forceful are you? Sometimes, customer service people in China need a bit of prodding to get them to try new things. I must also state that Discover does a pretty poor job marketing its (sweetheart) deal with Union Pay; there's no reason it shouldn't be the go to product for foreigners traveling in China. They clearly should get the word out to merchants, users, and Union Pay itself.