Don't use Eco Earth Loose coconut fiber substrate.

[Zoe]

in rare cases maybe, but would you rather be standing there picking chips of wood outta their mouth while they down the rat or let them eat in peace?
ive tried all the other substrates and none are less of a worry than ecoearth.

I think you might have missed my point... Did you miss the part where I said I was playing devil's advocate and that I do like (and use) coconut mulch? IMO it's one of the best substrates but it's not 100% foolproof (nothing seems to be when you hear about snakes eating entire pieces of paper towel) and I wanted to clear up some of your misconceptions about the issues surrounding it.

Incidentally, I have had a snake get it in his "cheeks". Lemme tell ya, getting that out of a GTP's mouth is no picnic! Luckily I noticed right away, and he is pretty tame, so it was quick work. It was because the substrate was dry... which is why I recommend keeping it somewhat damp. When it gets dry it flies around and sticks to everything.

and wait why would the rat/mouse be wet when feeding? mine are always dry.
with the exception of drool from my snakes.

Lots of people thaw their rodents directly in warm water... I do. I pat them dry in paper towel and I don't feed directly on the substrate but if you did some could stick to it. Again, it's usually not a serious issue, but it can happen and there is no harm in being aware of it and taking steps to avoid any potential problems.