I've been strongly against using VSS in the past for a number of reasons, one of which is the fact that it uses binary configuration files that are hard to edit and easily subject to corruption. One cosmic ray, one byte changed, and your repository could be toast. By contrast, I've been known to say, open-source alternatives like CVS and Subversion use more reliable systems with plain text you can edit.
It's interesting that I was so against VSS using binary configuration files thinking they were unreliable, because Subversion also keeps bits and pieces of binary files in its Berkeley DB binary database (by default). Of course, it has to use binary diffs in order to decrease storage space -- one of its key benefits.
Maybe it seems different because I've never heard of Subversion corrupting and losing information, and you don't need to run "Analyze" on it weekly to ensure no corruption has occurred in the last week.