-Boris-
The GPU transcoding won't load CPU cores much at all. They should be clos to Idle. And you can see the opposite on the Intel. CPU consumes more than GPU on the Intel in it's specific test, while GPU consumes more on Llano.
1) I was talking about Metro
2)
idle 43.6W
GPU trans-coding 126W the difference is 82W and the same discrete gpu with a bit higher clock as the IGP has a max. TDP of 39W 82-39=43W just for CPU if IGP is working at its TDP limit. So much for your statement how cpu is close to idle.

3) SB consumes more in Metro than in x264 Encode and if you don't know SB has Sandy Bridge Media Engine which is doing video encoding and decoding instead of GPU thats why the consumption is lower than in x264 Encode.