Hyatt looks after their Diamonds very well. It's worth holding that status. The challenge will get you into that exclusive club only once and after that you have to qualify on your own.
Diamond Treatment can vary though, some hotels go out of their way, others don't:
Park Hyatt Tokyo: Excellent Diamond recognition
Grand Hyatt Tokyo: They don't care
Park Hyatt Sydney: Excellent Diamond recognition
Park Hyatt Melbourne: They don't care
Park Hyatt Milan: Excellent Diamond recognition
Park Hyatt Vendome: They don't care