I'd go with a pair of N. brevis. They share a shell if they're a pair, so they're often easy to identify as a pair at the LFS.
Multis are great, but they'll quickly overpopulate your tank because they're such good parents (brevis have a tendency to be, well, less good at the parental thing).
So, the answer is yes - shell dwellers from Lake Tanganyika will do well in a 10 gallon tank with hard water!
Eric