I use EcoEarth for all my snakes, all the time. I have a snow, and it's much easier to see her on the coconut fiber than the aspen. It's also cheaper for me, and easier to store cause it takes up less space.
Just make sure that you don't soak it so much, otherwise it will be too humid in the tank. I put in about 1/2-3/4 the amount of water suggested and then break it down with my hands. This way you get a drier product. Or, you can soak it, then let it dry out for a day or two before switching out the substrate - not as easy in my opinion.
The only time I don't use it, is for a hatchling. The aspen is easier to monitor the feces for the first couple months.