I still have every Nalgene bottle made of polycarbonate/Lexan that I ever bought. I have never had one of the bottles wear out. I have had to replace a cap or two, the strap that holds them to the bottle takes a lot of abuse if used to clip onto a pack or belt with a carabiner.

Now, I have melted one of the polyethelyne Nalgene's, (fire will do that), <img src="/images/graemlins/blush.gif" alt="" /> and have cracked a couple cheap knock-offs (turns out a 200-foot drop will do that... <img src="/images/graemlins/wink.gif" alt="" />) The newer Lexan ones are pretty tough. Your mileage may vary.