I can't speak for CEX.io or others, but it walks like a ponzi scheme, and talks like a ponzi scheme, guess what!
I made a deposit at Zeushash they stopped paying after just 2 days. I have received an email suggesting their is "malleability" issue. If you are reading this and are thinking about buying a contract be careful. If you have funds there already, you may want to withdraw them now if you are even able.
In my opinion zeushash is a ponzi scheme, beware!
That's right zeushash already turn into scam. It's already smell like a ponzi scheme in the first time actually.
Cex.io already stopped their mining activity, but you can still trade ghs to btc.