I have older Firesticks so maybe a bit different, but always used them in the avrs rather than tvs (but any av gear I prefer to use the avr as a switching center, at least with my tvs). I did recently get HD models of Firestick (my older ones were also not 4K, but slightly older with a slightly different remote, altho both have Alexa I don't like talking to a remote). I don't care for hdmi-cec generally but the newer HD Firesticks do enable power/volume control of my avr using it, and aren't too bad but does seem to cause some issues when changing over to my normal Harmony remotes after using it (and does nothing for my bluray player or other gear connected to my avr aside from the tv). Overall I still prefer a Harmony remote using macros for control of the system generally, but not all my Harmony remotes can control the Firestick outside the ones setup on a Harmony Hub.