The light status would be a nice touch, but my ultimate goal is to use a single keypad button to mean "scene off" in the most reliable, responsive way possible.

 

If this is of primary importance, then I suggest including your single keypad button in the scene (as controller) and setting the keypad to non-toggle-off mode (sending only off commands when pressed). If the light status is something you desire, then use an approach like kingwr in the first post.

The program to control the status light of the KPL button in the first post does nothing to affect the reliability of the button action itself. In my case, the button is set to toggle. So changing the status light of the KPL button simply toggles the action the button will take if pressed: either turn all the lights on or turn them all off. The actual action of the KPL button is defined through a scene, and it works correctly everytime. I wonder if you could set the KPL button to no-toggle off, and still implement the status light program. In that case, it may turn the light on and off with the status of devices, but still always turn all lights in the scene off when pressed.

I wonder if you could set the KPL button to no-toggle off, and still implement the status light program.

 

Yes. Being in non-toggle does not affect ability to turn the button "on" or "off" from as a response to a scene command or program. It only affects action from a direct press of the button. I take advantage of this capability on my garage door buttons.