I have neither snails nor assassins now, but that's a feature of having central american cichlids I suspect. My ellioti seem to like eating snails, and I have about 50 of them at the moment spread across various tanks. It's a method of clearing snails that I hadn't tried before but is proving very effective.
When I had assassins they never did much more than bury themselves and eventually die off. Would love to know how you got so many, they've been a bogey stocking item for me.