It probably was an inside job to some extent. Some menial but smart guy was not really paid enough and said screw it, it worth the risk and gave himself a $5 Mill pay day.
It looks like they are going to have to multi sig everything.
Another thing I do when sending is to send a very small test amount to an address first just to see if it gets there. Once I see that hit, then I am pretty sure everything is ok and send the larger amount. Sure there is an overhead but hey you pay to minimize risk.
I agree with your approach.
Even when cashing out never send too large of an amount to an exchange.
Just recently around the last few days of 2014 I was tempted to send a large chunk of BTC to bitstamp to speculate with.
Thankfully my family time and coin business kept too busy to even get around to sending coins to BitStamp.
Yeah sure the price of bitcoin fell and I likely could have sold higher and bought more coins at a lower price but...the pure risk of bitstamp having a screw up like this was worth the lost opportunity to speculate.
BitstampBTC and BitstampUSD are worth nothing if they can't make good on all withdraws once they reopen.