If you're pushing around a LOT of files(which I did for a game project's data, the asset compilation process involved several copies and processing) Dropbox can screw up occasionally. If it's just a few source files that you edit in place you're probably fine. Also, some apps may modify files(e.g. a local database) in place without touching their date, which is scary since Dropbox will never update the file until you manually touch it.