I have ~65 Z-Wave devices around my house, and I definitely notice lag from time to time. Recent versions of Z-Wave seem to be significantly faster and I've noticed it less.
I can't say I _love_ dealing with Z-Wave. But I do like having a single protocol throughout my house. At the very least, any issues I have tend to be consistent. I'd say in this past 6-months, I've practically had zero problems. I blame that overall improvement on ZwaveJs, because some of these devices are at least 5 years old and they're just cranking away without issue right along side my more recent Zooz and Inovelli devices.
That said, I've been strongly considering multiple Z-wave hubs, each running zwave2mqtt with a central mqtt server just to keep everything as fast as possible.
The single protocol throughout my house was my primary goal too, just to reduce complexity of having to deal with multiple hubs and integrations... but with my new house I did away with that.
Lutron Caseta for physical in-wall switches, IKEA Tradfri for cheap motion sensors/lighs, Philips Hue for more expensive motion sensors/lights, and a whole slew of Thread enabled devices, all controlled from HomeKit.
I don't really notice that its a bunch of different protocols/wireless standards underneath. I can control it from a single location which also makes it easier for guests/people visiting. Hand them an iPad with the Home app and they can control the house, or add them a Guest to my home on their own iOS devices.
I do miss some of the more advanced Home Assistant stuff I was doing, but overall the experience has been much cleaner, and with almost 0 lag.
I can't say I _love_ dealing with Z-Wave. But I do like having a single protocol throughout my house. At the very least, any issues I have tend to be consistent. I'd say in this past 6-months, I've practically had zero problems. I blame that overall improvement on ZwaveJs, because some of these devices are at least 5 years old and they're just cranking away without issue right along side my more recent Zooz and Inovelli devices.
That said, I've been strongly considering multiple Z-wave hubs, each running zwave2mqtt with a central mqtt server just to keep everything as fast as possible.