Personally, I'd stick with aspen or paper towels mate, and this is why. Basically, Exo-Terra Jungle Bark is made using fir bark. Now fir trees are really closely related to cedar trees, and I'm not 100% sure, but that means that they could give off the same phenols that cedar does, which is toxic to reptiles.
Both the products retain humidity really well, which is great for reptiles from humid environments, but as I'm sure you know, Cornsnakes only need around 40% humidity.
Products with the word 'earth' in it, usually means that there's a whole host of creatures lurking within. I've seen it personally.
Also, poo can be really hard to spot on those substrates, which obviously can create problems.
Generally, aspen is a great substrate. It's cheap, looks good (IMO) and poo can easily be spotted. It's also great for burrowing. If you're concerned about your tank looking bare, then add a little colour. Putting in a few fake plants and some natural looking hides can make a huge difference. One Exo-Terra product I would recommend would be their Jungle Vines. Corns love to climb on them and they look great, especially when used with some fake plants.
I hope that helps
David