I have tons of the small ones that are nocturnal - along with Nerite, apple, and mystery snails in my tank...I never have seen holes in the leaves of healthy plants ~ instead they seem to prefer decaying, separated leaves, dying stems, and debris on the tank floor... Above all that, they seem to dig algae too! I was glancing through numerous "anti-snail" threads suggesting killer assassin snails, loaches, zucchini trick, etc...and wondered why the fuss??? Seems kinda a key to a healthy set up... Though the eggs are rather annoying and ugly at times... But wanted to hear ur guys thoughts ...
Also, came across this very brief read if interested....
http://www.aquaticcommunity.com/aquarium/snails.php
At first I was shocked to see dozens fall when I first turn on my rooms lights... Now its kinda a hoot as the disappear rather rapidly with the onset of the morning's (fake) LED sun....