I can just tell you that I invested almos 0.06 BTC into Hashflare (of course with a good BTC Price 11 days ago, which makes a difference in how much Hashpower you can buy) and I have now almost 0.005 BTC on this plattform.
So after 132 days I am even and if you think about the contract going for a year and calculate with fees and invested time I will double the amount in BTC. If this does not crash, everything is okay at using Hashflare...

i will multiply this answer so that everyone sees it because there are some similar comments.