That's very interesting! Rather than the headline number, I find the load rate of 1GB/sec more interesting. From the blog, it's not clear how large the cluster was. Useful to have that information too.
Disclaimer: I work at 2ndQuadrant.
We used a 16 datanodes, 2 coordinators Postgres-XL cluster for these tests. We'll be publishing more information with different cluster sizes in the coming weeks.