I toss them to my figure 8 occasionally. Originally planned for them to live there but he waits for them to open their door and rips them out. So far I have lots of pretty shells everywhere but no snails for cleaning, lol.
They live happily in my other brackish tank and are slowly populating a 40g fresh. I like them, I've deliberately added them to the 2 tanks they're in and unsuccesfully added them with the puffer and Ecat to no avail. They churn the sand, clean everything, so long as they don't reach plague proportions I don't see a problem. Really, I think if they get out of hand you need to adjust your maintenance somewhere.
Frequent hand removal with or without baiting or loaches are most effective I know of. Otherwise they are tough to get rid of. They tolorate fresh to near marine water, they can live at any temperature the fish can, I've left some in a bucket of gravel that dried up in hot weather and some survived.. Copper maybe?