Sorry to be a little off-topic, but I really like the layout of your site. I'm on a convertible and I switched to tablet mode part way through reading this and was pretty delighted to see all the notes in the margin pop into inline info boxes.
A smart home will definitely run those numbers up. I have about 60 WiFi devices and another 45 Zigbee devices and I'm only about halfway done with the house.
That is not the case. Only YouTube and Netflix have exceptions where the Android app on Google TV / Android TV intercepts the standard Chromecasting where the TV just pulls up the receiver web app in an ephemeral browser. And even for YouTube it'll automatically log you in in a temporary way when you cast. For anything else, casting to an Android TV device is exactly the same as casting to an old-school Chromecast.
Just to try, I just logged out of my Google Chromecast with Google TV (yes folks, it may time to rebrand...), and started playing a stream from Spotify using my phone.
And now I'm listening to Spotify.
I did this with both Google Cast and Spotify Connect (Spotify, at least on Android, allows selection of this).
No issues.
Am I not holding it right? It sure has the appearance of working correctly, but we may not be observing the same things.