Having looked at the Kudu paper & code yesterday, it's still early days. It might not be worth spending too much time on an evaluation just yet. Quoting from the paper: "In the current beta release of Kudu, this consistency support
is not yet fully implemented. However, this paper describes
the architecture and design of the system, despite
the presence of some known consistency-related bugs."
Generally, I'm glad about this very recent trend of moving back to C++, first with
http://www.scylladb.com/ for Cassandra, and now Kudu for HBase. We are spending a good amount of time working around JVM scaling & latency issues, so I'm looking forward to see these projects mature into serious alternatives.
Gabriel