The Journey comes with the tapered tip that fits platy bottles and similarly sized soda/water bottle openings. It might make more sense than using heavier wide mouthed bottles, if you aren't able to use a cooking container to treat the water.
For example, the platypus weighs 0.8oz, while the 1L nalgene collapsable canteen weighs in at 2.1. That is a difference of 1.3oz.
The Sterpien Adventurer weighs 3.6oz, while the Journey 4.5 oz, a difference of 0.9oz.
By choosing the heavier Journey, and the lighter bottle, you save 0.4oz.