For those of you who have experience, how good are Swiss Gear backpacks about holding up? I have an expandable one that costs about $65... I was able to get two case books, a bluebook citation book, and two other thin books in it, as well as my laptop. It all fits fine, but it weights close to 25 pounds. Do I need to worry about putting too much stress on the straps (afraid it might break on me), or do those bags tend to be durable enough that I shouldn't worry about it.