As mentioned here, HP RDX is a rugged, hard disk-based backup solution with native capacities that span four steps from 320 GB to 2 TB.
More than anything else, it is quite inexpensive to deploy.
We are in the process of replacing DAT installations at client locations with this fast solution.
More on RDX can be found here.
Our sincere thanks to HP, and especially Paula Dallabetta and Calvin Z. for making this review happen.