I don't mean hardware failure, I mean "intermittent, rare command failure" -- I've never experienced quite the same level of annoyance/rage from anything else, versus hitting a switch and having it either not turn on/off or having it be delayed by 1-second.
Granted, that was relatively rare, but having a wall switch not work even just 2-in-100 is enough to give me serious pause. I did love & do miss the ability to turn all lights off from a bedside switch, to run scenes, etc. -- but I'm just not sure it's worth the trade-off.