when i treated my tank i had upwards of 25 apple snails in there. i lost one shortly after treatment, but that may have been due to her being a heavy breeder (lotsa energy going into reproduction shortens the lifespan IMO).
the few red cherry shrimp in there at the time were perfectly fine after, also have a ton of ramshorns in this tank and they fared just fine. bn pleco came through wonderfully, as did cories, barbs, albino rainbow shark...... no fish loss at all. and nobody was stressed during treatment either.