I too had this set up. DirecTV HD DVR (not Genie) HDMI into the XB1 then to the TV. I had three issues
1. There is no standby passthrough which forces my wife and kids to navigate the XB1 menu just to watch TV
2. The picture changed, it was brighter, with tint issues. Reds would look orange, then switch back to red, and it kept flicking back and forth.
3. It made the menu and channel changing lag. It blacks out for seconds between channel changes.
For these reasons, it has been dropped. Microsoft has a bunch of kinks to work out here.