Forgot to follow up on the water bottles. Carried these around a bit, and when tightened to the same degree as USGI canteens, they are perfectly water tight. But, takes some deliberate effort to get to the same tightness. That minor difference I mentioned above in the shape of the lid grooves matters. Who knew design mattered?!
When next I see some dirt cheap surplus canteens somewhere, with good lids, gonna grab two and toss the bottles, trade the lids out.