Hi Fischer's Angel,
I kept several species at different times, including Oliva paxillus (now considered by some to be a synonym of O. nitidula...?), but I never saw them exhibit the super-predator behavior that I saw in other species. The most aggressive ones were Oliva sericea and Oliva miniacea, and I believe the Florida/Caribbean Oliva sayana behaves in much the same way. Oliva amethystina were also active hunters, as were Oliva caerulea, but I never saw them tackle snails bigger than they were. Same goes for Oliva carneola. O. nitidula (paxilla/paxillus) was the most reclusive of all the olive snails I kept, although any of them might disappear for weeks at a time. All of them would scavenge to some degree, and were attracted to dead fish or shrimp, but O. sericea and O. miniacea seemed to prefer live prey.
And yes, I kept lots of different snails, including about 35 different species of cone snails, but I never had a lot of luck, long term, with the worm eaters. Of course, they were in the tank with mollusc eaters, so I don't know that they had a very good chance at becoming long-term residents. The fish-eating cones and the molluscivores seemed to thrive, though.
Cheers,
Don