I was in this situation last year. After 8 years of working in China, I had much of my savings in RMB in a bank. I was pretty lazy about moving it out into investments, and since the RMB was appreciating, I didn't feel any pressure to jump through the hoops to do forex.
However, after the initial deprecation last year, I saw the writing on the wall, and got the money out. It wasn't easy, but it wasn't impossible either. Chinese citizens can exchange $50K USD a year, which doesn't seem to be going away, while foreigners can exchange what they earn in China...with proper tax documentation (it took a few weeks to complete my initial forex).
Investment opportunities in China really suck! You have the bubbly real estate market, the insider trader stock market, and foreigners are actually very restricted from doing either of both anyways (we can't buy stocks, acquiring property is tricky, not that I would want to do either). The only reason I kept my money in China was because of the appreciation, investments also weren't doing well at the time.
I can see the RMB being a serious currency..it isn't that messed up compared to say the Venezuelan Bolivar, or many currencies in SE Asia or even the Indian Rupee. Heck, the Japanese Yen is even more volatile, and I would have lost big time if I made bets on the pound or the Australian dollar. But the lack of convertibility, even if only partial, is a big show stopper. They really should make more effort to that, and they seem to have stalled for the last 10 years while walking backwards from the reforms of the early/mid 00's.