"That passthrough requires the xbox to be on though... which is a massive pain in the arse."
But necessary due to HDCP, meaning any kind of bridge device must be active to work. I believe those Google TV boxes had the same issue. But as for the power use, has anyone actually checked the One's power usage when it's just idling? I know from experience that electrical usage in PCs can vary significantly between humdrum desktop use and full-on gaming, rendering, or encoding jobs.