Moondog55 wrote:Is it worth going uber-lite if they become so fragile they become unsafe?
Probably not, but they aren't that fragile. A typical coke bottle is very, very strong and quite durable. I've never had one leak while bushwalking. If they get crushed and then you re-inflate them they start to develop creases which will eventually form holes. But even that takes time. I've only had it happen to bottles I'd used repeatedly for rock climbing, for well over a year.
I stopped carrying the regular coke bottles and started carrying the super thin water bottles, the ones that are kind of corrugated and look like they'd puncture if you dropped them. I retire them after a couple of years when they're all scratched up, creased and dirty, but I haven't had one fail yet.
The platypus bottles do wear out though. The plastic ages and cracks eventually, but it's not hard to spot that and replace in advance.
Even if you carry a steel bottle it's a good idea to have some sort of backup -- you could lose it.