Now they are adding US$ trading and hopefully more cryptopairs and maybe other Futures products, so I will continue using them for trading.
You have to look at how they market themselves 'Crypto Exchange' and not just 'Cloud Mining' If you just buy GHS and hope to ROI on the mining reward well that won't work. Rising difficulty will and is your enemy there. The opportunities with CEX are from trading for sure.
I never bought futures, although wish I had done. GHS are in a bear market so you have to trade it like that, buy on bounce back from dip (once support base is shown), set your stop loss exit just below support base and set an exit at resistance area once price bounces back up. These type of trades are short term and usually looking at 5 to 10% gains. Its not for everyone but typical short term trading style. I just closed out such a trade and show it below.