Paxos would be good for electing a master, but we wanted to avoid having any masters in the architecture. There are also scenarios where paxos can be slow or fail to reach a consensus. We wanted high availability from each node in the cluster regardless of whether 2/3 of the rest of the cluster were down or unreachable; both parts of a partioned cluster should also be able to continue to function as best they could.

Individual nodes can often make "personal" decisions about what to do in subobtimal situations. If you can answer an incoming request, even with partial or out-of-date data, do so; it's better than not replying. For the repair agent, each node can see its own view of "holes" in the 3-level replication, and offer to make copies of <3 buckets to bring back up to three copies.