Well, it's been almost a month since this thread started and my Nexus 5x with Android 7 is still doing fine. No battery problems. My biggest power user is screen first and cell standby second.
For me "Cell standby" is the biggest worry. Even with Wifi ON only when the screen is awake, cell standby consumed >20% e.g. when I have 20% battery left. Is this normal? Before Nougat I never saw "Cell standby" in the list (but the sum of the consumers didn't add up)