Well, good question. As a total amateur with only a couple years experience on this...and a mechanic that I trust...I have left the switch unplugged. It is neatly tied back in case I need to put it back, but it is not plugged in. I have driven this rig nearly daily, stopped and started on errands, etc...No problem yet. The plugs, ACs, go their merry 14 seconds and she start every time. In the morning or at cold starts, I have some white smoke that lasts for about 20 minutes.
The GP controller card works well, I hear and see the volts bump up after about 30 seconds of post start glow plug activity. Then a little later, the fast idle advance kicks in and the rpms drop.
I also have a manual glow plug switch under the dash fully wired and ready to just in case...hope this is helpful.
Sorta sounds like a no-brainer to me.