This may not be as definitive as you like, but this PC Magazine article says:
Basically, the ones with the light don’t short out because the light uses the electric path. The ones without the light can short out because of, well, they weren’t designed to be conductive.
I suspect some paint on the hooks of the cover will stop the shorting problem. Nice black paint will do, cover up any bright spots. Maybe nailpolish?
I’ve had no restart or other problems. I also received a cover for it. I think the hooks are plastic but I can’t check at the moment.
My mom has the K3 with the unlighted cover and hasn’t had any problems.
I went for the recent one with wifi only. I can’t imagine the scenario where I would need 3G access. The thing holds 3000 books on it (and an infinite number can be purchased and held for you on amazon) so if I’m going on vacation, I would just put plenty of books on it ahead of time. If I were desperate, I’d find a Starbucks, but it has never happened.
If it’s not too late, I thought I’d mention that Amazon now allows people to lend their Kindle books to others for 14 days – a feature that the Nook came with, and that many people had noted as a key differentiator.
Say, that’s swell! Maybe public libraries can support it now!