I would like to add some automated lights. I have several tasmotized sonoff and esp8266 devices on a HASS system on an RPi. I have read/watched how to stuff a shelly or sonoff behind a rocker style light switch. I don’t want to go this route - there is usually insufficient room as it is, and if I sell the house, I would have to remove it all (not a big deal).
I could go the z-wave route. I have used the jasco z-wave switches with frustrating success in a Vera system. With my Rpi, is the aeon zstick the choice to make? I also see a z-wave daughter card and HomeSeer (not looking for more hubs though).
I have a very good wifi system. Two access points to a router/switch system. It would be a shame to not just use that coverage. Are there any good wifi switches/dimmers for 2,3,4 way lighting? and that connects easily to HASS like the tasmota devices?
After researching a bit more, I am thinking a smart switch might not work when put on a multi-way switch (3-way and 4-way). I see threads discussing lack of feedback, and the work-arounds require more sensors and violate the kiss rule (though I suppose any home automation breaks that rule 
).
So the Shelly switches seem to be the top candidate.
The Shelly sits between any manual switch arrangement (2, 3, 4-ways) and the light. And I assume it would work on a 4-way (three switches and a load) as well. Can anyone confirm?
Second question: I see how HASS and a Shelly smart switch will turn on and off, and be updated on the web page, but how does does HASS and Shelly know when the manual switch system is turning on or off? I would guess the Shelly reads a change of state in the manual switches and then toggle the power to the load, and sends back to HASS?
The Shelly UI has options to change how it interprets the signal from the manual switch. It has a nice UI with MQTT capability. It does not have a group topic, but the full topic can be modified.
I assume any multi-way works the same way. I found this youtube that covers several wiring scenarios and it appears there are other youtube videos.