I think that it'd be super-valuable to do an analysis of an RDS Postgres deployment. Amazon is doing some dark magic with RDS that sits at this really interesting "distributed, but not that distributed" inflection point, which impacts the basic assumptions of lots of distributed database design.

I believe RDS Postgres is probably the right answer for lots of applications, especially for those that already depend on AWS for baseline availability. I'd love to see if that holds up against a rigorous analysis.