Your original post was to gain opinions on the substrate. While it is not as openly accepted in the snake community yet, it is widely used in the large lizard community. I don't have any input on springtails causing people to itch as I really haven't researched it, mainly because it isn't an issue at my house. What I can say is that my opinion is that using Bio-Active has had a very positive impact on my animals, and the statement about putting the animals at risk of bacterial infection has no backing what so ever. You essentially create a biome in which the environment maintains itself. There is no increase in risk of infection vs using woodchips or matting. Some even argue that matting or woodchips harbor more bacteria because it absorbs waste, and if not cleaned frequently the bacteria builds up, as there is nothing neutralizing it.