Well, my research basically went round and round in circles. Many people posting advice were basically guessing formalities based on information that was unclear, different people at different times had had different experiences and the information was conflicting itself all over the place.
Not sure if you were able to look at this forum's FAQ Sticky, but the information there on Transit Without Visa is current and accurate, and definitely not guessing.
At Fukuoka I'd been given boarding passes for both legs and I waved these at the clerk at this desk, but she said "No good" and pointed somewhere in the opposite direction, saying I should go to the first floor then up to the third floor. Err…OK…
The "No Good" translates to "you can't go this way."
Turning around, I saw the only way out of there was through immigration. There is NO airside departure lounge! Everyone was filling out Arrival-Departure forms and since, bar one or two people, they were all presumably Chinese, there was nothing clearly indicating they were in transit like me. There were a couple of airport staff sitting by an X-ray machine off in the corner, and I showed them my boarding passes and asked if I needed to complete a form. They said I did, so we duly filled them out (there is only one kind of card, so the part asking for my address in China or whatever I just marked 'Transit') and went to line up in the clearly marked Foreigner line.
Correct. Chinese government policy currently requires that all international arrivals including transit passengers, must go through immigration and border control. This is also clearly in the FAQ and many posters on various China forum threads have attested to this. These procedures are not new.
...but when it came to my passport she called someone over. Visions of Richard Gere jumping roofs in the movie Red Corner…but he just signed something in my passport and I was through. The officer told me to go down to the first floor. At least there was consistency as far as which floor I was meant to be on.
Chinese officials aren't nearly as unreasonable or scary as the uninitiated seem to believe. Often junior officers manning an immigration desk will have a supervisor come over to do the sign-off for intl transit passengers--at airport terminals where there is no dedicated desk just for intl transit passengers. Not to worry.
Bit of an anti-climax really, after all the research I'd done and conflicting - or at least ambiguous - results. Bottom line is: make sure your passport is in order, expect to go through immigration with a completed form even for transit, and remember which floor you're on.
Thanks for posting a very detailed post-mortem.