Power efficiency, your cpu draws around 65 watts full load. Which isn't much, so yeah.
And yes, 8gb is really unnecessary, because you probably won't go over 2gb doing whatever. I know for a fact you really won't be using this for gaming, obviously, so that's why I said to get less ram. And 1066 is very slow compared to 1600, it's worth it, and as I said earlier, the 4gb has a latency of 9 along with the 1600, so really if I were you, I would be getting the 4gb.
I'm making an apu build soon, and the ram I'm getting is http://www.newegg.com/Product/Product.aspx?Item=N82E16820231460
(promo code) EMCJNJD37
APU's benefit greatly from faster ram, it's worth it.