I have the version1 Z-Max. It puts out a much higher voltage than the screen tells you and so if you are not careful it will pop your low ohm coils cartos etc. I'm sensible with it though, use standard resistance kit on it and like it. I am ware that Alba Vapours withdrew the sale of the V1 and did a recall. I'm not aware of any safety issues as such.
The V2 has by accounts solved the issue but if you're in any doubt,don't purchase.