Some questions, some answers.
If you need your editors or customer to manage files, the FileBrowser is an alternative to an FTP-client. Moreover, with the FileBrowser you are able to define different image-versions according to your websites grid.
Grappelli is a requirement for using the FileBrowser. There are several filebrowser-no-grappelli versions (most of them on GitHub), but we don’t follow the development.
The FileBrowser is about managing files. We think that you should prepare your files before uploading them to the server.
We have discussed this issue on the Grappelli Google-Group. Since the outcome has been ambiguous, we stay with svn for now. Of course, the same is true for the FileBrowser.
You need image-versions if your website is based on a grid.
We’ve developed the FileBrowser for a couple of years and use it with almost all of our clients. That said, Grappelli is the more stable and mature application.
Help is very much needed and appreciated. Test the FileBrowser and submit feedback/patches.