I know of no snails that do not eat algea.
It is a myth that snails will control algea, it is also a myth that snails will live on algea alone long term. It is not a myth that snails eat algea. They can and will control small quntities of algea and give a very polished look to a well maintained tank.
MTS's are excellent glass cleaners, but are slow and it takes a good number of them to make any real dent in glass algea. They do not do much for plant leaves. IMO there is no downside to MTS's in a tank.
Dave
