I think the majority of pilots opoerating in and more important out of HKG are aware of the "mainland" problem.
My point is, as long as there is no other means of flow control, slot allocation or metering, however you would like to call it, why not tell us that we have to wait due to, in this case, outbound traffic or a release from "the mainland" or what so ever.
To get me right, flying to a lot of odd places around the globe, HKG atc is doing an excelent job, especially when keeping in mind the tiny airspace and the before mentioned "mainland problem". I am not fishing for compliments here, just to get this right.
This forum is a good place for ALL participating in aviation to share their opinions and last but not least to ask questions, rise concerns or even make a suggestion. Comunication is verything as we all certainly know.