check the china and other asia forums for china travel. Service levels and FFPs are discussed there. Personally i would stick with SQ and fly *A. MU's service is probably best, and although i do accumulate points through their eastern miles program, their FFP is nothing special. But i still prefer it over asia miles. Within *A CA and FM are pretty standard for mainland airlines.
When i requested status matches with local carriers here, i was laughed at each time. This is something they have never heard of.