Yes I have used them, and they seem to be doing well on them. I keep carrots with mine, fruits and water gel either go bad or dry up fast. I have bred Dubias for years now, and one thing I can tell you is to keep them warm, I have mine over a heat pad and that made a huge difference in the production as soon as I used it.
Their staying in 80F room which will be plenty warm for them.
I guess i can experiment with the water crystals till their gone, and see if their easier or just using the fruit/veggies for the water.