Just in the same way as knowing multiple languages can help you know your own language better, I believe the same goes for database management systems. This competition between vendors of varying DBMSs allows for great features to be passed from one database engine to the other and benefits us, the DBAs, greatly. The benefits of taking the deep step into another RDBMS can further enlighten your approach to resolving problems or creating unique solutions that embrace a resolution no matter what source they come from.
Seasoned Oracle DBAs I enjoy working with have mentioned the lack of spooling in Oracle's developer (UPDATE, actualy spool does work fine in O.Dev 2.1), and after going back to using SQL+ for a while they have a very good point. Oracle Developer and SSMS always have the code / results split up (unless in SQL DMO?), which doesn't always make it easy to associate the error with the section of code you are working on (unless you click on the error in SSMS report pane that is). Setting the Spool on and off after working on production provides pretty bomber evidence for auditing operations on your production databases, or results during testing and development.
PS enjoying a little work with PostgreSQL also recently, converting a schema to SQL Server and Oracle.
Really enjoying the tool SQuirrel SQL Universal SQL Client Version 3.1