Its a good Question. One time my Antivirus showed the exe as a Virus but it is not. I googled it and i found this Page https://forum.minergate.com/viewtopic.php?t=1524. It market that as a Virus because of the background mining operations. By the way if you want to, you can find Leaks on every Software.
Payment Security: I didnt made a payout yet but i saw a video where this was happen. You just have to hit a Treshold amount to make a Withdraw.
Upto now i found no bad Information on the net and im still using it.