Re: Pitfalls of G.fast
What "safety grounds" are you talking about? This is a few watts of DC power at a low voltage that can't hurt let alone kill.
As for paying for power, if you are worried about the bill for powering something that requires 7 watts when it is running and has a low power mode when you aren't using the internet so the average will be less than half that, you must have really really really really high "retail electric prices" to be concerned. Just think of it as your internet bill costing that little bit extra every month.