Very nice to see how people use our products in action. Nice project and very well done so far, congratulations.
A few inputs from my side:
If I were to start over, I don’t think I would change all that much, but I haven’t lived with the system yet.
I will start with this. In Europe, Middle East and Asia such a project would probably be realised with KNX. Some things would have been probably easier (rotary dimming, nice designer push buttons), some things like changing the fade time on the fly probably even harder than what they are now.
That said, I needed many more inputs than the 12 on the SmartCore. ESP32s with MCP expansion boards offered a lot of GPIO for little money.
Another option would be to use DALI-2 binary inputs, see here, there exist even models that allow 8 push buttons to be connected. Considering that a DALI-2 system supports 64x DALI-2 sensors (next to the 64 DALI lamps), that would be a theoretical maximum of 512 push buttons which must be more than enough.
Integrate a lot of motion sensors throughout the house. I am using wired sensors by Faradite. These are also basically contact closures
Same goes for these Motion Sensors, you could have used DALI-2 binary inputs, and would then have much easier wiring through the house. A single open loop (all topologies allowed, e.g. star, tree,…) can interconnect all DALI lights, and sensors. There even native DALI-2 motion detectors, that at the same time have integrated sensors for humidity, brightness, temperature and air quality. See here.
I also needed to figure out how to use the 0-10v dimmers as control inputs for my DALI lights. The 0-10v dimmers are only two wires; there is no wiper pin. So, to use them with the ADCs on the ESP32, I used a resistor between the GPIO pin and the ground.
Rotary dimmers are indeed so holy grail, congrats on your solution on how to implement that. Another option would be to use rotary encoders, instead of 0-10V sensors, meaning you can endlessly rotate and have no absolute values. This allows to dimm the light (imagine you first twisted the knob to 10V, then dimmed down using HA, and want to dimm up again by twisting) in any situation. There exist some DALI-2 solutions, that can often be fitted right into the metal plates and knobs by companies such as Forbes and Lomax (we have done this multiple times with Meljac), or see here a solution for KNX with 4 external rotary knobs.
Anyways, huge congrats on your project, looking forward to more insights. Especially how you will do Blinds, Curtains, HVAC and Door Access. All interesting extensions that could be realised in many ways, one of them being Atios SmartCore 
