I worked as a contractor for the Wisconsin state government and they had hundreds of Oracle databases that they were consolidating on the Oracle EXADATA11 servers. Insane having hardware that can only run Oracle but the Oracle DBA said that the Exadata was dozens of times faster than Oracle on VMware VMs.
Lies. Fucking lies. We were a three environment shop until we moved to Exa and the compute/$ ratio is so bad that we had to cut it down to two.
But we're talking about Oracle here so that's par for the course.
I didn't make any claims about performance per $, just relative performance compared to VMs. I hate Oracle as much as anyone but the EXADATA is impressive hardware. It has lots of RAM and Infiniband networking. It can push query predicates to the storage controllers to reduce the data that had to be transferred.
It is impressive. But for the same cost you can get vastly better performance with Postgres and bigger hardware.
It does come with internal redundancy, but do you need that? Also the cluster nature of it can come with some surprises as compared to a single database.