The past couple of days have shown that when gox is down, the other exchanges can't cope with the overflow and they go down too. I accidentally put my user ID in wrong on Bitstamp and it turns out there are only 5 spaces there, so they hadn't even imagined getting over 100,000 accounts. Bitfloor have been down a good part of the last 18 hrs and have some mysterious holds on my funds (which have all been deposited since the return from the hack).

I seriously doubt that any of the other exchanges has the capacity or the resources to scale bigger than gox. Compared to what they could and should be doing, they are rubbish, but compared to where the other exchanges are, gox are still miles ahead.