David,
I take 50 minutes connection everytime I travel from JFK-HKG-TPE/PVG/PEK, and I can tell you so far I have never been disappointed. In fact, this is one of the reason I'm sticking with CX. Like Dr. HFH said they already know who is on a "tight" connection and usually will have an agent with your name on it (with others) and after all have arrived the agent will escort you through the connections security line (i.e. cut all the way to the front.) Then, the agent will walk you to the gate of your departure (or point the way if it is too far and he/she doesn't feel like walking there.)
Luggage-wise again I have never had an issue. However, if you want to have an ease of mind do ask the gate agent if your luggage has been transferred aboard. They can find that out easily.
CX dares to sale you the 50 minutes connection because they know they can deliver. Now, of course this is barring a freak of nature (like severe thunderstorm, etc.) or technical problems, then yes, you're screwed.