A couple of thoughts about the very moderate efficiency improvement. First, I wouldn't be surprised if they are just reducing the hashing board voltage by 1-2 volts. You can do this on the D3 with the Blissz firmware and it lowers the electrical usage without seeming to lower the hash rate. (sometimes undervolting even improves it a bit.) I also notice that they are quoting AC electrical usage as +10% now. If my memory isn't completely out of whack, I recall they used to quote it as +/- 5%. Anyone else remember this?