Well, security is relative. On mtgox, they were more secure to price volatility, since you could sell them any time. But how can one be sure if any service is secure to the theft.
Ah not much, around 1.7 bitcoins. Bought them pretty cheap (<$300) in the recent weeks because I wanted to take the bet. Turned out I lost the bet. But that's not a big deal, I made around 1 bitcoin profit through btc.sx.
I used to mine bitcoins and have them sent to MtGox (in tiny fractions of course) but stopped doing it long before as this process became too inefficient.
