But there is NO SPEED in wifi so all this investment will feel like you were ripped off. The common powerline speed is only 84 megabit which is slower than common ethernet but still good enough for playing HD Video. I know this since I'm using simple shared 54 meagerbit 802.11g to link down to the media room and it's all good.

Makes me wonder why you think you need to go gigabit networking.
Bob