I was also wondering, other than the quality issue, if it is better to get something like a backpack to spread the weight, rather than use one side or another.
I think for heavier loads, backpacks are definitely the way to go. However if you are only carrying a few files or a laptop, these are nice enough to work in more casual workplaces. Timbuk2 does make backpacks as well, though. They are my favorite brand of bags, but I only buy them on sale or heavy discount.