I heard this a a great card to get for the convenience. I understand you are allowed 3 days free use of the MTR. I am going to be in HK for 2 nights, going to China for 3 weeks and coming back for 3/4 nights. Is it better to buy the Octopus card when I come back as then I can take advantage of the full 3 days?
Alternatively I could buy one when I arrive, get a refund before I go to China . When I come back, I could buy a brand new card to get another 3 days MTR use. Is that a good idea?