I'm also a big fan of Perforce for large (especially internal) repositories. It handles just about everything smoothly and is also free for Open Source. That b

I'm also a big fan of Perforce for large (especially internal) repositories. It handles just about everything smoothly and is also free for Open Source. That being said, I've really been enjoying working with Mercurial. I think the biggest shortcoming I feel is not being able to branch (easily?) subdirectories rather than repositories.