A few years ago while staying in a 5-star hotel in Guangdong province, the hotel's ATM machine "ate" my ATM card (even though the correct logo was posted on the machine). The hotel had to call a special "task force" that arrived at the hotel about a half hour later to open the machine and retrieve my card. It was all actually quite funny, because the "team" was about 5 guys, several who positioned themselves in the hotel lobby with machine guns drawn! It was like they were opening the door to Ft. Knox.

Perhaps, with more experience, more rational procedures are now used to address this problem. That said, I think I'd try to bring 2 ATM cards with me to China -- just in case.