First time a senior dev overrided my choice, and to my dismay we did a pure DB solution that took longer and was far inferior in its version control capabilities than if we had done it in VCS/XML.

Second time I was in charge and pushed this "great idea" through. We ended up with awesome branching, cherry-picking, diffing, etc capabilities (which were not in the requirements and nobody really used), but ran into big problems later when we needed more thorough data consistency checks, incremental non-GUID id's, speedier centralized inserts/updates, etc. Second step was rube goldberg, and third step was rewrite given the actual requirements using a normal db store (probably half the code, better performance, easier to use, no "extra" VCS functionality that nobody needed).

Lesson learned: don't use VCS as a data store unless it's kicking you in the face. Or, maybe there's a market for a VCS with some DB-like properties.