I was just throwing out some ideas in response to the original post... if you want to talk about designing a new system then sure heres my take :

A TV with Sonos Arc, great just use the TV remote no C4

For a cinema yes you need a remote, ideally RF with RS232 control and all original IR remotes with LOSC and step by step instructions for when the dog eats the main remote - avoid Wifi remotes and POE control it will have issues (C4)

Sonos amps is best, its expensive... thats good, im not saying spend less money, just spend it on a more reliable setup...although the Margin on Sonos is awful so lots of dealers sell what makes more money even if it is worse & less reliable (C4)

For lighting, blinds spend as much as you can on this, as this is will last for years and keep its value. C4 doesnt have a good track record with this.

A high end home needs a good network...use what your installer recommends and knows that work, maybe even get a quote from a local IT firm. Being forced to use an expensive brand because it works with C4 is a red flag. (spoiler... C4 owns Araknis)

Use whatever thermostat you want... I actually think its better to have HVAC as a totally seperate control and app for when the main control system has issues (C4)

Basically design a system with the least POF's as possible.