i only have the 8505 box and mine has an average usage of 12% and it eats around 16 to 18 watts in that state (thats with usb adapters drawing power from it and a huge ass fan laying on top of it, running inaudible at minimum rpm, which is not necessary, but allows the cpu to stay on turbo basically infinitely).
it eats up to 50watts peak, averaging around 48 watts, when i hammer it with cpu stresstests such as s-tui
the i3 and i5 units should be similar on idle, but draw more power on load, since they are more powerful.
its also dependant on the configuration in the bios.
i allowed my cpu to use up to 30 watts (default is 15), so my power usage under stress is higher.
but this has no influence on idle, or near idle as my cpu is sitting on low speeds when its not busy due to powersave governor.
im sure there is more opimization potential there, but im quite happy with the thing.