Re: Feeding on Eco Earth?
I use EcoEarth! Feeding on it hasn't been an issue for me. Not a ton of the substrate gets on the prey, and from what I understand, snakes are able to pass it since it's coconut fiber, and it shouldn't cause impaction.
To avoid getting substrate on the prey at all, you could use something like a plate, a bit of cardboard, or something similarly stiff to keep the prey off of the substrate (not paper towel, so that the snake doesn't eat that). This is a good idea to do especially if you feed with wet prey.
Re: Feeding on Eco Earth?
Pretty similar to the above, in my experience. I mostly feed prey damp, not dripping wet, so I just pat off excess/dripping water before offering. I've never really bothered trying to get them to eat over a plate since mine all seem to drag it off elsewhere. I've never noticed much stick to even damp rats, so I doubt it would be a big issue.
If the feeder is really wet, you may get more substrate sticking to it. Since eco earth is a coconut fiber, it would take more than just a little bit to have much risk of being an issue. As long as it doesn't look breaded in it or caked on thick, you're fine if they eat a little bit.