I live in , and therefor my links are for where I purchased from. There may be better (and most likely cheaper) sites in your local regions.
The wall switches are not actually used they are brand new in box they don't fit properly and I decided before they arrived that I preferred the standard wall switch look as our house is in a hampton style and these were a bit too modern looking. If you are interested I'd be happy to sell them at half cost price message me over in the forum jimpower.
There is nothing special regarding the hardware used when I start to notice available hardware resources becoming exhausted I will look to move to another platform.
Lately I have started to notice the automations becoming sluggish and this is due to the resources of my HA Server becoming occupied with background tasks like device tracking and sensor polling. With the recent release of HASSIO on its new operating system HASSOS I decided now was a good time to upgrade and splinter my automations off my main HA instance onto a dedicated RPi. Splitting my HA tasks across 3 Pis has made a huge difference and my automations have become snappy again whilst all my sensors can run in the background not effecting the performance of my essential tasks. I used the MQTT Statestream to keep all the Pis insync with each other. I have used Hassio with standard Add-On store packages which include Appdaemon for use with HaDashboard, Mosquitto Broker for MQTT Broker & Node-RED for more complex Automation flows. I have now installed a stand alone RPi with Grafana, InfluxDB and Node-RED to take the strain off resources on my HA device and to also have access to a larger hdd for database storage. My config in this repo is a combination of all my Pi's as if you were running it all of the same device to save confusion message me if you would like more info on how I splintered off the automations to a dedicated device.
*** I have now moved across to using an Intel Nuc i7 running Ubuntu Server with HASSIO in a docker. This move has been amazing and the install from start to finsih took no more then 30-40mins. I still run seperate pi for MQTT Broker but have moved my Automations onto the Nuc with Node-RED also running in a docker container. My reboot times are down to 55s even with alot more being thrown at it great move and I highly recommend it if you can justify outlaying more coin for you HA server.