SVN is much simpler than git for the simple stuff (checking in files and updating them when everyone's online), and much more complex than git for the complicated stuff (branching and merging). Or put another way, git's learning curve is steep up front, and then increases moderately as you do weird things; SVN's learning curve is very shallow up front and then increases rapidly.
If you're storing large files, if you're not branching, if you're not storing source code, and if your team is happy with SVN and the workflow you have, I'd say you should stay on SVN.
If you're writing source code with a relatively modern development practice (developers doing local builds and tests, pre-commit code reviews, preferably automated testing, preferably some amount of open-source code), you should move to git for two reasons: first, this style of working inherently requires frequent branching and merging, and second, your ability to interact with outside projects is easier if you're all comfortable with git instead of snapshotting the outside project into SVN.
