Maybe check here also before you invest:
https://bitcointalk.org/index.php?topic=173316.msg5632280#msg5632280You can check the difficulty here on this page:
http://bitcoinwisdom.com/bitcoin/difficultymobodicks 20% rise per month is rather conservative. It's actually closer to 20% two to three times per month instead of just once.
Currently the Gold contract will cost around 6BTC and I'm afraid it will mine not even half that amount during the contract period. So far cloudhashing has yet to come up with a decent reply on these concerns about the growing difficulty.
What i was refering to was that you
need it to be lower than 20% to make anything back on those contracts if you don't use rrp. Of course the
real difficulty goes up much faster and no rrp will be able to compensate so basically nooone will make a return on investment, nevermind profit.