If you're happy with what you're using, then you're not missing anything, paul.

I carry a backup 1L Nalgene Lexan Bottle, but keep equipment in a heavy duty waterproof bag in it until such a time when I may need to use it. If the Nalgene bottle fails, then I also have a roll of Gerber Seal & Go Breastmilk Bottle Bags... LOL

I also pack a Reliance Fold-A-Carrier collapsible 5 gallon PE water jug in my BOB, and have two more in my car.

Every piece of equipment we carry can fail or may have shortcomings. It's all about finding what works best for our own purposes. If a person is happy with what they have, then that's all that matters.