For anyone of you with access to the roadmap/feature requests:
is a great, web based filemanager and would be a perfect companion to ISPConfig.
One thing that is very important is to be able to unpack compressed files on the server. Installing a CMS that has several thousand files (Joomla has 4000+ files) takes a lot of time if you need to upload them one by one. Uploading the zip-file and unzipping is not only faster (by a magnitude), but also more secure - less chance one or more files gets corrupted in the upload.