We have two junior bottles, which pack easily into kids lunch bags or hiking gear. While the bottle itself is very durable the lids are not.
The flip cap initially seemed like a great choice for kids but it fell apart with daily use and requires removal of small rubber pieces for through cleaning. Therefore we only carry water in the bottles. Scrub as I might the rubber pieces have darkened with evidence of mold or bacteria growth. Bottle will leak without rubber parts and wrack my nerves trying to keep the small parts from falling down drain during cleaning.
Additionally, the flip cap cover appears to be attached with a piece of hollow aluminum and has fallen off one bottle, so just one more thing to keep track of.