Lets say a site gets hacked, in theory, the fiat $ is a lot safer because the bank will usually simply not allow the hacker to make a huge wire transfer, but the bitcoins can be transfered instantly So when the news of the hacking comes out, investors can then wire out those funds and avoid any kind of BK/mtgox problem and keep 100% of their funds thoughts?
At Mt Gox and recently Bitfinex you could not get a wire transfer out so you had to cancel the wire and buy Bitcoin trading at a significant premium to other markets and transfer them out before they went bust.
Keep the absolute minimum at a Bitcoin exchange. Wire money in, buy bitcoin, transfer bitcoin to the wallet on your PC.