I work for a moderate-sized university. The applications I support require up-to-date information in order to test modifications. They are read-intensive with few writes within the database. We can afford only one test database for the entire university. We refresh the database from production only once a quarter, at most. My applications would benefit greatly by being able to switch URL's to the production database in order to test a mod. Since our code, written in PL/SQL, gets stored in the database that it runs on, we can't do such a thing without significant effort: dblinks or modifying package names to store in production for testing or a test schema or whatever else you can think up.

Another issue is that PL/SQL is not a robust language for modern development. Its type-system was designed for strictness, which is great in life-critical systems. But, there is no notion of inheritance and no ability to write generic collections.

To mimic inheritance, you can create objects backed by tables and inherit one from the other. It has the feel of being bolted on and yet another tie to Oracle.

One final issue is that PL/SQL is highly subject to the resource management of the Oracle kernel. Often, the kernel is extremely efficient. But, there are times when you need code running in a separate address space, preferably on a separate server. For instance, one application I wrote is a batch system that has a lot of processing rules built into it. Our database is tuned for OLTP. My application is categorized by the DBA's as data warehouse-oriented. Yet my application has to run hourly throughout the day and compete with resources necessary for the OLTP stuff. Putting it onto a separate server, away from Oracle's kernel management, would more than likely help a performance issue we have.

So, the answer to your question is the one you were looking for. But, my concern isn't necessarily switching database vendors.