Creating a viable competitor is never a victory from a business perspective.

I have half dozen Hue bulbs, and they seem rock-solid - far more stable than my Lightify bulbs.

The HA SkyConnect does seem to be a factor. For a while, my Lightify bulbs were the last thing on my old Samsung SmartThings hub (via the HA integration- basically using the ST hub as a Zigbee radio/stack), because they operated more reliably there.

Yes, every line-powered device is (probably) a repeater. Many light bulbs are, with the caveat that you must keep them powered all the time. Having a bunch of repeaters drop offline will cause fits with your mesh stability.

Make sure to look for Zooz blueprints - there are blueprints for many switches. The blueprint for the Zen32 scene controller really helped me use the switch to the full extent.

Zigbee is notorious for mesh instability, mostly because some devices (looking at you, Lightify) are picky about what repeaters they use in the mesh. Build your mesh slowly, spread some good repeaters around your house, and give the mesh time to settle down before using it in production. Don’t move repeater nodes or power them off. (I had some lights that I had to delete and re-add every two weeks, until I figured out that the cleaners were unplugging a repeater to plug in their vacuum:-) Finally, make use of the “Visualization” tab under Configure to see what’s happening on your mesh.

Certainly reduces the confusion - one less car brand to consider when shopping.