Originally Posted by
illico
As I understand it, I will need to cross immigration/customs, pick up my bag, re-check-in and pass security.
Not if your bags can check through. But it is fine to assume this is the worst case scenario.
Originally Posted by
illico
I have the HK E-Channel on my passport. Is this 2h45min window enough time, or should I just book a later flight?
Doable. As you can image - the problem is not immigration/customs, but baggage delivery. As soon as there is no major delay, my estimate is you should be able to get back in airside within a hour after your initial arrival.