yes, using the -k option of git stash allow you to 'put away' the changes which are not in the index.

The argument of creating a broken commit is natural, but not very relevant IMO: after all, with svn and co, the risk of forgetting to commit a new file is pretty strong as well. If you care very much about having non-broken commit, the only reliable solution is a gateway that merge commits only after they pass a test suite.

Highly recommend git-svn for committing from git locally to svn remote

Even if you are on svn, you can still use git. The svn bridge works quite nicely.