I have probably twenty scarlet hermits in my 70, with pretty much every common and uncommon available macro and have no issues. I assume they munch on things a little, but I've never caught them in the act and I bet if they eat it, it's already on its way out.
Emeralds and blue hermits, about the same experience although they seem hungrier than scarlets, and are both more aggressive.
(Just to be thorough, for snails I have astreas, florida ceriths, margaritas, zigzag periwinkles, nerites, and dwarf planaxis (all from reefcleaners) and they play nice with macros as well. Turbos I'd stay away from)