Nowadays, a software system's program source code makes up only a small part of its assets stored as bits--taking up a larger percentage are specifications, design diagrams, application server deployment scripts, build rules, version history, documentation, and regression tests.
How is the situation in your organization? Can you easily move your design diagrams from one UML-based tool to another, change the repository where your specifications are stored, run your regression tests on a different platform, or switch to a different configuration management system? Unless your organization still uses paper records for these tasks (in which case your problems are in a totally different league), chances are you dread even the thought of changing the tools you use.