From my experience, it seems that overclocking the S2 just makes little sense.
Replacing the PSU (and paying an extra $350) + increasing load by 0.5amps just to get an extra 50 GH/s seems more risky than the value it will bring.
Would love to see what other people think.
Thats what I also concluded and stopped. Its just not worth the time, power, potential for failure or effort.