I wouldn’t worry about immigration, it hasn’t been an issue for me with a quick turn around. A tip I recently learned is to sign up for the e-channel in Hong Kong, so you can avoid the immigration waits and agents. Right after immigration, but before going through the entrance to baggage claim there is a place to sign up for e-channel. If you miss it, like I did, there is another location in the city. Bring your frequent flier membership card, since that I saw one way for eligibility. Happy flying