Couchbase Server Rolling Upgrades
Sean Poulley's statement that Couchbase Server does not support online rolling upgrades is false.
Couchbase Server has supported online rolling upgrades since before the Couchbase Server 1.8 release. For reference, Couchbase Server 2.5 is the current release. Online rolling upgrades are a key component of the Couchbase Server foundation. In fact, while we support offline upgrades, we recommend online rolling upgrades to our enterprise customers. For years, our enterprise customers have been performing online rolling upgrades to Couchbase Server in on-premise and cloud environments.
While Cloudant's work on scaling will be greatly appreciated by the Apache CouchDB community, we have yet to see an Apache CouchDB release that it includes it. Thus, it has yet to be proven by the community.