Tarsnap has been working really well for us, but one huge downside that we've noticed is how slow it is to restore data from say a 1TB archive.

Sometimes it takes more than 3 hours to restore a customer's 40MB directory.

If we were to have a full HD failure and had to restore the whole 1TB, that would probably take days. Days of downtime for us.

So depending on your situation, this might not be ideal.

I contacted Colin about this a few months ago and he mentioned that he is working on a faster version.