Yep, that's the only way to do it with zero risk. But since btcchina.com is consistently higher than the other top exchanges you'll eventually have to move CNY out of there and bitcoin in. Moving bitcoin there is trivial (which shows how great bitcoin is) but moving CNY out and converting it to USD for the other exchanges is trickier (need a Chinese bank account for example) so I would expect the lag in price to continue.