The thing we really strive for with Postgres is to keep the UPDATE traffic as low as possible. Because of MVCC, table bloat and the subsequent vacuum jobs will kill your IO even further. This means designing the applications and data model in a way that most write traffic is INSERT, with occasional UPDATEs which cannot be avoided. If you know you are going to have a UPDATE heavy table, be sure to set the fill_factor on the table ahead of time to optimize for it.

Also, in my experience "Faster SSD Storage" point applies to both read and write heavy workloads.