I bought a Fibaro Dimmer 2 and the Scolmore switch to build a test setup. I intend to redo the entire house for smart lighting when I replace my roof and build a loft conversion. As such I am not using the Fibaro for real but my test setup did work with the switch and Smartthings when it was setup.
I used the DTH as from the following thread.
I also programmed the Fibaro module so it was setup for use with a momentary switch as per.
This requires programming for a 3-position momentary switch and also using a 3-core plus earth cable between the switch and the module. Older UK lighting circuits only have 2-core plus earth. My plan is to rewire during my renovation project.
I since setup an Insteon micro dimmer module with the same physical switch and it also worked both with the physical switch and Smartthings using a different DTH. My ultimate goal is to have wired switches and smart lighting control that work with both Smartthings, Alexa and Apple HomeKit. Fibaro is unlikely to meet that requirement in terms of HomeKit but Fibaro does offer the ability to do everything else I wanted such as mixing dimmers and switches, supporting pull-cord switches and so on. Insteon have indicated they plan to release a new hub which will add HomeKit support but it has been a year since and nothing yet has happened. I could in theory use HomeBridge to add HomeKit support but would prefer and official solution due to the danger that Apple will kill HomeBridge at some future date.
I have been looking for a smart lighting solution for a long time because I have my own tough criteria but I recently discovered a new not yet shipping product which sounds hopeful. It sounds like it would be a lot more expensive than either Fibaro or Insteon but will have official HomeKit support and supposedly will fit easier at the light switch end whereas Fibaro and Insteon realistically need to go above the ceiling rose.
As my home renovation project is still some time away from happening I have been able to research, experiment and wait.