The only ZigBee I have is via hue, and I'm okay with that. I'm focused on zwave, the only reason the ZigBee (hue) stuff is even here is because it was my first smart light system and the bulbs still work, over time I've bought more and more bulbs to satisfy needs, and now I have enough that it would be a bad idea, financially, to rid myself of them; so they stay until I decide otherwise. Mainly for separating my system from the rest of the house and because the Mrs is already used to using them.

For zwave, I have a number of inovelli bulbs and lightswitches that serve as routers/relays for zwave, they're not fully deployed, so the mesh isn't as strong as it could be. I have a few areas to install that will be done soon, like the living room and rec room (I already did the majority of the bedrooms hallways and whatnot). The main issue I'm running into is that I need to turn off power to install the switches safely, and that's always a challenge in a living household, but they're connecting to mains power, so they act as routers all the time, even the bulbs, the switches have a "smart light" mode which keeps power on even if the lights are set to off; it's a big reason why I chose these switches specifically. I still have some significant gaps in the mesh from the areas not currently converted. I have the bulbs and switches, so it's just a matter of turning off the power, sorting out the wiring and getting the new switches installed, then installing the bulbs, on-boarding them to the mesh as I go, and building the relevant automation to tell HA which switches should control which lights.

My plan was to have smart lights with switches in every area except the bathrooms and kitchen (possibly garage too) for safety reasons. I don't want someone inadvertently (or intentionally) turning off the lights in those rooms while they're in use, like if someone is handling a knife in the kitchen, or hot food, or if someone is in the shower, where they may trip and fall while trying to turn the lights back on while slippery and wet...

Bedrooms, hallways, common areas, etc, are all marked for at least a switch, and usually a switch, bulbs, and a multisensor (Aeotek multisensor 7 has been my go to, but it's not a relay), for environmental monitoring (temp, humidity, light and motion (partly for presence, I know that's not the best indicator for presence, but still).

Back to the matter at hand (no pun intended), the lightswitches and bulbs should be plentiful enough to act as relays/routers for the mesh when I'm done, since they're in almost every room, on almost every wall. If I need a dedicated relay/router for an otherwise weak area, I'll see if I can get one that's specifically a relay/router. I know such devices exist (like the - now discontinued - Aeotec ZW189 "range extender"). I don't think that's going to be required.

As for zwavejs2mqtt, as I understand it, zwavejs UI can do mqtt, but for me, I currently have it turned off, since my zwave controller is directly plugged into my home assistant. I'll probably need to experiment a little since things are evolving so quickly and the tools are changing quite a bit.

I appreciate that the system is not designed with multiple controllers in mind, I was thinking of it for redundancy more than anything, but that's a fairly rare thing in consumer goods. I have backups and that will have to be good enough.

I toyed with the idea of smart plugs, but I don't want warts all over the walls. It's a personal preference. I would like to have per outlet power metering, but it seems there's few, if any, in-wall receptacles which accomplish this without significant compromise (many are only rated to 12A, won't support inductive or reactive loads, and generally only monitor one of the two outlets in the duplex - I only want monitoring, not switching, and I don't care if it's for each receptacle, or both combined, but I couldn't find something viable, and decided to go with new, standard receptacles instead. I'm planning to still do power monitoring, but at the service panel and instead monitor individual circuit loads, but I want something that's either hardline Ethernet, or zwave and there's not a lot of options that can monitor all circuits which meet that criteria, Aeotek has one that monitors just the service power (input at the panel from the electric service) and that's zwave, but won't do individual circuits, there are DIY versions, largely based on the ESP32, but they only seem to connect by WiFi, and wifi is extremely poor in the area where the service panel is (I'm also trying to keep smart home stuff off WiFi whenever I can), and I didn't see many other options apart from that (there are some that are wifi only, and if I was going to go that way, I'd just build the ESP32 version myself).

I'll keep looking, but at this rate, my best solution may be a smart service panel. I want to upgrade my electrical service from 100A to 200A as-is, so it might be the direction I go.... I need a new panel anyways, might as well get one that's better for my goals.

I want to thank you for this very interesting conversation. This has been helpful in all respects. I appreciate your thoughts on it, and I hope you have a great day.