(dis)advantages of staging dev->production using 'drush rsync' vs 'git'?
I have used both techniques.  Both can be used to guarantee that the same files that you test on @stage end up on @live.  The advantage of rsync is that you do not end up with extra files (e.g. ".git" and associated) on your production server.  I tend to rsync to a vps, and use git on a box I own (e.g. intranet sites).