The G19 has a programmable set of events that you can code for with lua for each key and each mode. This is distinct from the basic macro / hdi setup.

Some distinct examples I have my backspace key throttled when in M2 to only allow a set number of key smashes per second, after that number is hit it drops the backspaces and doesn't pass them.

In M2 when I press H/J/K three times in a row within 2 seconds it will remap key for backspace to be ctrl-backspace until I press numpaddivide (my all in one / buff / smartres button). This is a hack for when I freakout at the keyboard and want to do some healing, but I have the healer dedicated to a rotation of some sort ctrl-backspace is what the multiplexer expects for a all dps minus the healer.

The keyboard knows how many copies of wow I am running and the paths (even if you don't allow the wow modules to run), you use that potentially. I have not looked into knowing if the character name is available to the key events. Potentially that could be interesting.

When my multiplexer is toggled off, certain keys are noop ... breathalyzer key essentially.