Jim:

I can't speak to climbing and summiting; I hike in the eastern US, so the highest "peak" I've summited is about 5,000 feet (if you count the 70 feet of trees on top.)

However, I'd expand your advice to include general backpacking. I've always had great skepticism about moving out of eyeshot of my backpack, whether it's to do a little bushwhacking or dayhiking, or even just to trot down the little side trail to get water. (I think Colin Fletcher was also somewhat paranoid about this.) I always figured that keeping my pack with me pretty well eliminated the chances of critters (including the two-footed kind) making off with gear, and gave me a little insurance that, if I got injured on that little side trip, I'd be able to stay warm, dry, and fed until help came. It also eliminates the chance that someone will decide to become an instant geologist and start his rock collection in my pack. (Nor would I ever think of doing that to anyone else )

Especially with the light loads most of us carry nowadays, I heartily second the advice: always keep your pack with you; it might come in handy.