From the project website:
Elliptics network is a fault tolerant distributed hash table object storage.
The network does not use dedicated servers to maintain the metadata information, it supports redundant objects storage and implements transactional data update. Small to medium sized write benchmarks can be found (its the latest to date, other presented earlier) in the appropriate blog section.
Distributed hash table design allows not to use dedicated metadata servers which frequently become points of failure in the classical storages, instead user can connect to any server in the network and all requests will be forwarded to the needed nodes, one can also lookup the needed server and connect there directly. It can really be called a cloud of losely connected equivalent nodes. Joining node will automatically connect to the needed servers according to the network topology, it can store data in different configurable backends like file IO storage, eblob backend or using own IO storage backend.
Protocol allows to implement own data storage using specific features for the deploying project and generally extend data communication with infinite number of the extensions. One of the implemented examples is remote command execution, which can be used as a load balancing job manager.
Hard to say which of the NoSQL solutions will make useful backends or other components in a topic map system.
But, I would rather err of being inclusive.