Thanks! I guess I won't count on being able to transit airside ... I will have a multi-entry China visa so I'll just exit and check-in with SQ.
Check-in or the SQ flight should open 3 hours prior to departure, so by the time you have disembarked, done immigration, picked up the bags and gone upstairs you won't have long to wait (maybe 30 mins or so).
I won't have long to wait -- should I interpret this to mean that disembarking/immigration/customs/SQ-checkin/security/immigration will take a long time? I thought a 4 hr window would be sufficient on a Thurs night.