Here are real efficiency numbers at the wall:

S1 : ~2     W/GH
S2 : ~1.05 W/GH
S3 : ~.78   W/GH
S4 : ~.69   W/GH

I can personally confirm S1, S2, and S3 efficiency numbers using a decent gold power supply and kilowatt to measure power usage at the wall, but am using Bitmains published info for S4 efficiency.