Our current backup system is (while reliable and doing much of what we need) a dirty hack written by me so we can use deduplication to save disk and tape space. I'd like something more robust and cross-platform.

I need:
1) deduplication,
2) backup to disk and then from disk to tape for archival purposes.
3) I need Linux support and agents
4) Exchange and MS SQL support

* by which I mean they actively support it and have no plans to break this functionality in a later patch.

What are you using that a) supports the above, b) you're happy with and c) isn't a dirty hack?