Foreign passport holders with an eChannel sticker have no issues entering and departing via Terminal One at HKG airport.
Note (end of November) that when checking in at Terminal two, the eChannel readers do NOT support the reading of foreign passports with bar codes and exit must be completed with an immigration agent.
Given that from terminal two you will be taken by bus to terminal one, the walk might be useful if you have the time.
Happy wandering.
Fred