This last difficulty adjust could have easily been a negative .07% if the blocks had fallen slight differently. A stable difficulty is great, a stagnant BTC price of $230 may well tend to keep it there a while longer. Even if you are manufacturer of the ASIC gear, doubling your farm hashrate doesn't really help much, because a couple of weeks later a positive difficulty adjustment just washes away any gain you had in your hashrate. And unless you installed more efficient gear, you doubled your electric bill, however large or small that may be.
It's possible that the mining community at large has figured out that an ASIC "Arms Race" doesn't really help anyone for very long, unless the BTC price also increases.
Yeah if your farm has 1000 s-5's standing pat works if you power is low cost.
Lets say the s-7 comes out in sept 2015. and lets say it does .35 watts slowly replacing those s-5's and keep your hash exactly the same works since your power drops quite a bit.
In the mature Asic market this is a sensible money move
ie 1ph burning 520,000 kwatts vs 1 ph burning 350,000 means my profit goes up the price of 170,000 kwatts
