When should one switch from MySQL to Oracle or PostgreSQL?
My answer to When should one switch from MySQL to Oracle or PostgreSQL? on Quora
When your own benchmarks prove that your application’s particular load characteristics will perform better on another database—and the difference is large enough that it’s worth the cost involved in retargeting your code. If that cost is high (and it probably will be) it may be worth paying for some expert consultants to ensure that your implementations against the different databases are properly optimised.
External benchmarks and reports for products as similar as these will rarely teach you anything useful about your own particular situation.