There is very little that is technically interesting about Chinese derailleurs. The various manufacturers produce almost identical ranges of copies of the Shimano Tourney range.
What is fascinating is the appearance of a large number of producers since 1990, and the fact that most of them are based in the city of Ningbo. This is strangely reminiscent of the explosion of activity in the 1950’s and 1960’s in Sakae (Japan) the home of Shimano, Suntour, Sakae Ringyo (SR) etc. etc..
In the West, Chinese derailleurs are currently treated with the disdain that was reserved for Japanese products in the 1960’s. Whether that will change and a new ‘Chinese Shimano’ will arise out of the sea of pressed steel and rivets that is produced in Ningbo is yet to be seen.