Liquidity is the key factor when it comes to the crunch. And how can you please estimate the liquidity of an exchange? Only the order book gives you an idea how well the platform is filled with money.
Liquidity goes both ways. Mtgox is filled with money that nobody wants very much. Do you think that the people who offer to pay 5-10% more than they would have to on other exchanges and still don't get their orders filled agree that the liquidity on MtGox is good? The trade volume clearly shows that the liquidity is there on Bitstamp if you put up an order in the right price range.