Good points, thanks. On huge pages: this is also about RDS vs self-managed EC2 Postgres. RDS effectively has "on" by default, but default self-managed (that I benchmarked) is "try" which is effectively "off". I'll update the methodology page to cover that, and, yeah, it makes sense to cover that separately.

io2 is on my future-work list. And agree, I have the same feelings about IOPS.