Hainan had a very bad rep for excessive line training as of 2 years ago. A couple 73 guys I know were in training for over a year and both came current with >10k PIC on the 73.
I also heard from a recruiter(the owner of the agency) that the 330 ccq and a very high failure rate. Like, all of them.
I think BCA and Tianjin were both better places to work.
My personal knowledge is 2 years old.