The water crystals are awesome w/ the dubias, wouldn't want to try and raise them w/o them, but they can't get all the water they need from fruits and veggies. I have tried the crystals w/ the meal worms, it does work they love them, but the crystals are messier w/ the mealies, they tend to bury the container in the substrate and fill the lid w/ frass. If the lid is small enough or you have enough insects they suck it all dry before any mold or anything develops, but while the frass gets wet (before they dry it) it does have an unpleasant odor. I would only use the crystals w/ the mealies if for some reason I didn't have access to fruit or veggies or was having a confirmed problem w/ lack of moisture.
Thanks for that info. I was hoping to find someone who had actually tried it. I was giving it some serious consideration, not for nutrition of the worms but simply for hydration. I guess sometimes it just seems like the moisture in a potato, carrot or apple just wouldn't be enough with a lot of worms. Evidently is it, however, because when I put a fresh veggie in the bin they don't just "swamp it" like they did when I first had them delivered.