No I havn't used this. However the tall tails of it's use turning snakes into prunes after a day or two are obviously just that. Poor keepers looking for somthing to blame I'd think.
You do seem somewhat knowledgeable on the topic, and know that it is pretty close to pure H20. Any problems associated with such pure water lie in it's name. Osmosis. Atoms free to move will do so from areas of high concentration to areas of low concentration. When a snake drinks typical water, it is still of lower electrolyte concentration than the snake's tissues. This is obviously natural and easily compensated for by the animal. However this is the reason why ill or dehydrated animals are given such things as gatorade, or ringers solution ect. No with RO water, there is a much bigger gradient to compensate for. Obviously your snakes are doing fine with it, thus it is do-able. If any risks were to be apparent, you might see it on neonate animals, or new imports or otherwise compromised animals. The minerals in water don't really go towards nutritional supplementation in snakes (whole body prey), so that isn't much of an issue.
For my opinion, I think there are more con's than pro's regarding RO (having to buy it being one of them), so I don't use it. I don't think it's necessarily a poor choice to use it though.
I hope this helps somewhat
Ian
