I am mining with HashFlare since June 2016. Investing into lifetime SHA256 and Script contracts. Invested around 2700USD over period of 9 months. At the day of today I nearly mined as much as I invested. On February 2017 they have improved hardware and scripts and BTC price rocketed up in price. So it gives nice return since. Problem is that they don't offer lifetime contracts anymore and all my hashflare bought be for they cinverted to new 1y contracts effective from 1sep 2017. Quite illegal step taken from their side as terms and conditions shouldn't affect egsisting purchases. They just fooling their investors (means Us)
I hope that will clear out your doubts in case of investing.
Hashflare answered the question itself. I wouldn't wonder if they would shut down their site soon. Who would buy hash for double price with low power and for only one year?
The fact its really not profitable because the difficulty is not stable and i think you are just wasting your money if you invest there it takes a long time or you will never recover your investment in hashflare..
If you really want to make profit better to buy altcoin instead or buy more bitcoin because the price of bitcoin is increasing fast and i think you can make a good profit if you can invest more in bitcoin ..