I worked on a Doc. in China and Hong Kong in July 2008, I use wireless blocks 20, 21, and 22 and had no problem finding clean frequencies.
Before we went, we ( crew and producer) did the same kind of research you're doing now and almost universally we got this advice. If your production is small enough to fly under the radar, then fly under the radar. The more interaction you have with officials, getting permission to use certain types of equipment, getting permission to go places officially, etc.. The more red flags the production raises, the more they are going to say NO. It is just the way the system works in China. If the production is large enough to have a fixer smoothing the way, then they should be able to answer any of your questions.