I just tested this out an saw no real power-savings. At most it may have dropped my power consumption by under a half watt.
There are far more obvious things to fix here other than those ones.
like patching a browser for low cpu usage, reducing the amount of wakeups caused by the trackpad in laptops (this by far is the worse cause).
I wish canonical would refocus from boot time to powersaving. Does not one think of the children,