I'm betting an economic setback in China will be worse than something equivalent happening in the US. We in the US have seen recessions, we've seen the stock market crash, we've lived through economic bubbles popping. No one's ever happy about it, but panic is kept to a minimum because we've been there, we've seen it, we've lived through it.
China is a different kettle of fish. Modern China has gone from increase to increase. There's an entire generation that has never seen their market falter, never seen their GDP decrease, never seen an economic bubble burst, and have never seen a market crash. The instinct of quite a few Chinese will be to panic. It's a natural reaction, and it always makes a crash so much worse. The Chinese government's hamfisted reactions certainly won't help. They have always been big fans of using a sledgehammer when a scalpel is the obvious choice, they'll probably do the same thing here.