I personally used only MetaMask and have met no problem so far. However, in order to transfer token from MetaMask to an exchange, I used to connect my MetaMask to MEW to perform the task.

I have just found that we also can connect our MetaMask to EtherDelta exchange and perform transferring task without any trouble.

Above are my experience. And I have a question that "Is connecting MetaMask to EtherDelta safe"?

Thank you in advance.