Hi, This is my first post so if I have broken any stated or unstated laws I will try to do better in future.
About PB: I've bought 2 smallish contracts so far, joined in mid-March '14 and earned 0.308 BTC so far, I'm approaching ROI within a couple of months. With fluctuations in bitcoin value, isnt this an estimate anyway? My thought is: who's to say any cloud mining start-up will be around in 5 yrs? If I can make any profit within the time PB Mining is in operation I'll be happy. Right now there is somebody who has 28 TH who has earned 3.8xx by mid-week, not too shabby. If you join and buy a contract just make sure to send the exact amount - you will usually get your mining started real quick. GHs Price fluctuates depending on BTC fluctuation, as far as I can tell.
PBMining has been responsive to me when I was concerned about their website changing substantially. I too am skeptical of online joints but so far they have been real good. They have posted how much GHs they have available so you can see that without having to commit to a sign up. Only downside I'm aware of is not being able to sell your GHs back if you decide to get out. On CEX of course you can do that.
In answer to someone's question about PB vs CEX, one reason GH might be more on CEX is that they claim lifetime ops vs 5 yrs on PB, also you can trade and mine on CEX/GHash so those are good perks. Both sites have a lot going for them but be careful in how you manage your btc on cex. Had zero problems with PB so far (3 months). Hope that helps a little.
pretty good you thought,
but it's best if you have the funds would not be used in the near future may be good,
but if you traded funds are the funds used GHS everyday would be very difficult for a 5 year contract, and the funds can not pull anytime we want,
it should of course we looked pbmining, the view of each person is different,
I till now only survive on 19 gh / s on pbmin