I'm right there with you on PostgreSQL's impressiveness... I love it and use it everywhere.

However, having done a decent amount of database performance analysis, there is a very good reason I've seen to use Oracle instead of anything else:

Oracle scales more consistently linearly on the biggest variety of workloads compared to any other RDBMS. Give it more cores and it is the RDBMS most likely to give you more performance no matter what you're doing.