Here is how I see it...

• Bitmain: S4 2TH, 1400W
• KnC: Pluto 8TH, 4500W
• Spondoolies: SP50 12TH, 6000W (4X PSUs)

I think we've pretty much found the ceiling with .5W/GH.  Now we only have to know about the selling price for all of these.  With Bitcoin price in big trouble, development is sure to slow.  This should favor BitMain which develops on their own money rather than pre-order.  Bitmain might be the big winner.  

Will the S4 arrive before Christmas?