I have tried beer, hand picking and avoiding watering in the evenings. Of these hand picking is the best.
I have not tried the slub bell.
My very best experience with slugs and snails are introducing bantam chickens into the garden. They will eradicate all slugs and snails. After that you'll get snails from the neighbors.
I like the Silkies because they are docile and don't scratch deep holes. You need to keep them away from any sprouting seelings as they will snap them up.
Miniture ducks I think would work even better, but they are hard to find.