the basic red legged, scarlet and blue legged are usually reef safe. The blues are more aggresive and might eat your live snails also, for their shells.
Technically they don't eat the live snails. They evict the snails from their shells and take the shells over, the snails die in that act and they go back later and eat the carcass.
In my 14 years of keeping my tank, I have never seen hermits attack healthy snails that were on the glass. Unhealthy, dying snails will be quickly put out of their misery...and the occasional Astrea that falls on its back and can't be righted may fall victim too....but I've never seen them go after a healthy one.
My halloween hermit has attacked turbo snails for the shell...my dwarf blue legged hermits will mess with nassarius and nerite snails but eventually give up when they see the shell has an inhabitant