We use Amanda to backup to tape and it works great!
Actually, though, your request and requirements seem to need an organizational structure along with the backups to tape. If you allow many different users to push them to tape, that could get messy with tape usage efficiency. What I would do is provide shared space on the server which is specifically labeled for archival requirements. Maybe name a couple of shares after the regulations that they will meet. Then have directories with ownership and access for those people who need to put stuff there. On the server side, you would guarantee that data on those shares will meet those regulations. Then you make it so with whatever means necessary. You could have snapshots for immediate protection in place as well as a regular tape rotation and taking tapes out of rotation for archive.
By taking that approach, you put the responsibility for getting the data on the server with the person whose data it is. Then you manage the server. The whole arrangement would be more manageable.