Tha exchange is cool, why you are selling now ?
I mean what kind of update do I need to make it more secure ?
I sell the exchange due lack of time. I spent more than 15 hours a day in dec 2013 - Feb 2014 to keep the exchange alive, unfortunately number of exchanges rose from 3 (dec 2013) to maybe 25 (march 2014 - until now)
And I was not lucky enough, skilled enough, to be top or one of the tops.
There was cryptorush.in scam, where devianttwo (owner) took around 1000 btc from clients, so reputation of all small exchanges was dramatically decreassed
To answer your question:
There are no known security issues. Script is unique and build from basics.
If you want to run your own exchange you have to spend 10+ hours a day in front of pc, you have to have unique ideas and must differ from others, you have to take customers from current established exchanges (mintpal, cryptsy) to suceed
