What's your take on getting into Hashnest (at least to try out). Is it worth waiting for the new S7 units in one month? From one perspective, there is always going to be newer units on the horizon. From the other, I wonder how it would impact prices on the current ones. For example, if it's going to make the S5 2x cheaper, then it's probably worth waiting the 3-4 weeks.

Just running through the math, at the current rates, the S5 is $384 for 1150GH/s of hashing power. Assuming BTC's value stays flat:

At a 3% difficulty increase per month, you're looking at a $458 revenue, which is a $75 profit (20% annualized) in the first year.
At a 5% difficulty increase per month, you're looking at a $29 profit (7.5% annualized) in the first year.
At a 10% difficulty increase per month, you'd lose money in the first year.

Do those estimates seem correct? Based on your earnings from 20015-06-08, you're making slightly above these estimates by the way - maybe just a lucky day.