I completely agree on the power costs.
Here in Denmark, power cost is $0.40/kWh.
180 GHS gets you around 0.020 BTC per day. On the S1 that is 0.36Wh * 24h = 8,64 kWh = $3,46/day = 0.005 BTC or thereabout.
That is already 25% of the mined BTC going to power here. If I can get that down to 12.5%, it would be nice. And the miner would be sustainable for a longer time.

Now I have solar power, on my root, I am taxed on that, so using my own power instead of selling gives me a power cost of 0.1$/kWh, but I only have surplus production of a few hundred kWh/year. Can't expand my solar installation without getting hit by new stricter tax rates (where I can't store surplus energy in the powergrid for free, but will have to sell surplus for low price, and buy back at the 0.40).

Power costs is important, especially in Europe. Enjoy cheap power where it is, but at some point, the power costs will be more than the mining output. When the S1 is worthless, I can still earn 5.6 * $3,46 = $19.4/day on an S2. Don't know what will happen to difficulty when older equipment starts hitting the not-profitable line.