I guess that I am mainly concerned with the bike getting up and walking away while I am asleep. On my first tour I actually had nightmares at night that people were taking my bike and I was in my tent snoozing. I just read some interesting stuff about tying on or more of your tent tie downs to the bike at night and possibly adding a few bells. If I stop at tourist destinations where I might want to go walk around for an hour or so and then get back on and ride for the rest of the day then a strong lock doesn't mean jack with the panniers still there for the taking. In those situations I usually leave the bike with a employee in the security office or where someone can watch it.

I also have one of these laying around that I used to use in combination with a U Lock. http://www.rei.com/product/800078
It looks to be pretty strong but it costs $9. Is that really going to be safe? And it weighs 311 grams WITHOUT a pad lock. If I add in a crappy or decent pad lock then it might be a total of about 500 grams? Does this sound like a good option? I am not really sure what a good padlocks weighs.