If we are talking about the same snail (Neritina natalensis) then I can say yes they are plant safe. I have one in a planted 20gallon and it has never bothered my plants. It does a really good job of cleaning the glass and decorations in the tank though. And they sure are nice looking snails.
So they eat the dead plant matter and not the plants?
excellent, I've got tonnes of MTS to put in my planted tank but I don't want them in there because I've got laterite underneath the regular substrate. I don't want them burrowing around and mixing the two substrates together.