I have a residence visa and my Business requires that I am travelling in and out of China on a regular base, at least one to two times per month. No problem. I think you have received some false information.

So far I never sent an instrument out of China, but I had two guitars sent from overseas to China. One was send from the U.S. to China via USPS / China Post and the other one from Germany via DHL / China Post.
Both instruments arrived here in perfect condition. They were packed in the sturdy Gig Bag or in the Hard Case inside a simple carton box, which, however, was filled with material to prevent the cases from moving inside the carton box. I wonder if it would work the other way around as well. Shipping time was in both cases around three weeks. Both shipments came by air with low priority, that's why it took so long. Definetly refrain from sending it as checked luggage. This way I ruined my 12-string guitar, although it was packed in a hard shell case, designed for this purpose.

Flying a lot in China, I made a lot of experiences, good and bad, with all airlines. However, it is not always the airline to blame. The ground handling services are often "Outsourced" to the airport services and at least for Kunming airport they have often enough proven to be fully incompetent. It starts with their language capabilities (no English on international check in), not recognizing foreign passports, not knowing the transportation rules for the airline they are serving (luggage allowances, etc.) and ... and ... and... . Generally being a very patient person, recently on a few occasions I simply lost my temper, always on Chinese airports.