Some airlines have a transfer restriction pertaining to bags. For example, for Continental luggage can only be checked-through if the layover is 12hours or less. Check with CX to see what their policies are so you're not stuck in the airport with large bags and nowhere to go. As long as you make sure your Passport is one that doesn't need a visa to enter Hong Kong, or if you get your visa beforehand, you're free to leave the airport.