Wil,
I have spoken with some of my Christian students trying to find out which denomination their churches are, but they have no idea of the concept of 'denomination'. They are completely unaware that there are different types of Christianity, such as Catholic, Protestant, Methodist, etc. Also, I have not been to any of their church services, so I don't have a first-hand view of which denomination these churches probably are.
By the way, I have also spoken with my Buddhist students, and they too have no idea of the different types of Buddhism.
Religion in China is a very difficult topic for Chinese people to talk about. As the article says, the Communist government has been very successful in destroying most forms of organized religion in China, and the few that remain have become heavily controlled and indoctrinated by the Communist government. The whole idea in this article is that these Christian churches are trying to strike out on their own, be free and open, not be heavily controlled and indoctrinated by the government, and it is becoming increasingly clear that the Communist government will not allow this.
Another point made in the article is that Christians are becoming the largest 'people-group' in China, and this clearly has the Communist government worried.