Re: Grounding a Switch
There's really no danger, per se. In a worst case situation, where you plug into an amp that has an extreme fault, and is applying voltage to the ground terminal of the guitar jack, that voltage will be applied to your bridge and strings, which will be a much greater risk than the switch.
I only have the 5-way switch grounded on one of my guitars, and even then, only because it was a convenient place to tie grounds together. (Tele)