I plan on using coco fiber for a substrate, and never have. My concern was the fiber getting caught in the snakes' nostrils and heat pits, but this seems a bit over-dramatized. Sand, I could see; that could definitely be abrasively shoved into the heat pits. But I just like the ides of having a substrate that provides the snake a bit of cushioning to sit on. I used to use newspapers for larger amounts of snakes in tubs/racks, and still would if I get more snakes and it's cost-effective, but for now I plan on going with the coco fiber. I got the loose fibers that are not in a brick and don't need to be watered to separate/loosen. It'll also help to hold humidity better when needed.
Your thoughts?