Truly minimal original firmware but with the tasmota firmware is really satisfying, then with the atmega328 controller added I had excellent assistance from the technicians to configure the J3 virtual switch as a button, to better adapt it in the home system.
This product runs great with Tasmota, https://github.com/arendst/Sonoff-Tasmota,which is a great firmware, so I never tried the stock firmware. The case itself is nothing fancy but who cares, the dimmer itself is not visible in the room anyways, and it is tiny so it fits almost everywhere. The circuit as a whole is compact and can easily be installed by it self without the case, but be aware there are live pins which have no insulation. I do not use an external knob to control the dimmer, so I have no idea how well this works. Shipping was done within one day. The documentation is detailed and I had no problem finding what I needed. I had no communication with the people of Armtronix but I find no reason not to give them 5 stars.
EDIT: 2020 I have 2 Armtronix single dimmers running flawlessly for 2 year now. In this time I tried out some other dimmers as well, all running Tasmota. I would still recommend the Armtronix dimmers : 1) Pins already in place for firmware flashing, no soldering needed 2) Plays really well with Tasmota * Fade is working as it should * Can work with brightness <10% * No flickering whatsoever * I use Philips LED dimmable bulbs, product code: 871869648132500
This is a very well designed board. No DC adapter needed. Just hook up mains and easily control a mains device via MQTT or HTTP. I used it to control a 110VAC solenoid valve via home-assistant(https://home-assistant.io/).