Bought this devices 2 year ago, it work 24/7 without any problems!
Really good quality product!

I'm using Tasmota firmware

Although the product itself looks OK, the firmware is NOT! This product is only interesting if there would be a good working Tasmota firmware available. For the single dimmer it is! and that one works fine in Domoticz...So please guys, do something about it so I can promote your product on Facebook!

Product: Raspberry Pi Isolated IO, 24V

Pros: All four inputs and outputs worked right out of the box
provided documents makes mapping to the IO easy
works with Rpi.GPIO
24V power is very useful for cleaning the wiring
Fuse helps save precious electronics

Cons: Would have really liked the option to include standoffs in the order (as an add-on)
Wish the IO was sourcing rather than sinking
Shipping....

Notes: Shipping from India takes a very long time (like 30 days). In my case, it took almost 2 months before the correct product was at my address, and whats worse is I more-less spent an extra $10 to get it because when I received the incorrect item I had to pay to send it to the proper location (the other side of the USA). The person that received my item was not so nice and never mailed me mine so I was stuck waiting for another shipment from India to USA. All in all, I would say if you are looking to find a 24V IO HAT go to adafruit and get the automation HAT from pimoroni, it's a MUCH shorter wait time, you won't have to deal with costly shipping errors, and it does most of the same functions with a couple small trades.
In summary, I don't think I'll be getting any more items from armtronix when it comes to professional projects, it's not worth it, time is money and the time wrapped up in shipping nearly cost me the project.

Project (for those interested): This item required added circuitry due to it being NPN rather than PNP but I did successfully use it to allow communication between a raspberry pi and a Universal Robot. The pi handles a stepper motor which runs a linear rail with inputs from the robot telling the pi where to send the stepper. The pi is also running a computer vision system and telling the robot where a part lies for proper orientation of the gripper before pickup. Programming could use a little extra effort but all in all the system works.

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.

I have the single triac dimmer, rev 0.3
I really would like a tutorial (not only uncompleated text) on how to flash to arendst\ Tasmota firmware.
If you could provide a picture of how to connect it, and how to flash (esp8266 + ATMEGA328) with the use of a .bin file and ESPEasy, that would be greate.
The 'How to customise firmware' have no drawings, and figure 6: Other Header doesn't provide info wether it's turned clockwise or ccw compared to the picture in Figure 2.