I am not an expert in this area but in August '14, I had a 12 hour layover in HK and wanted to go to Lantau. I asked at an airport counter about doing this and they said this was probably not a good idea, due to the potential hassle at immigration.
I do not know if the advice was correct but I decided not to chance it since I was staying 5 days in HK on the return.
I was traveling in business so I made use of the lounges. BTW, IMHO the CX lounges are not all that great. After what I had read about Cathay Pacific I expected spectacular, but they were ordinary.
Had I not been planning a later stay in HK I might have gone ahead with my plan to visit the Budda temple, but since I was not familar (at that time) with all the transportation options and it looked like rain was coming, I figured why chance it.
Originally Posted by
stargold
Your biggest problem is not the "leaving airside" aspect, but the "leaving Hong Kong and re-entering without travelling" aspect.
If you were in transit, it is no problem to use the lounge first and then clear immigration. You will be entering and leaving Hong Kong the same number of times, just with slightly different timings.
In your case, you will leave Hong Kong, enter Hong Kong again on the same day, and then leave Hong Kong once more on the following day. I would expect immigration to say no or potentially give you a load of hassle when trying to leave again. Not really worth the effort - your friends will be better off meeting you landside.