Hi Ed,
First off, you HAVE to use the H680 card. Nothing else works.
The most important choice is software. Absolutely, 100% stay away from Retrospect. It is now a complete piece of shit for tape backup. Seriously terrible. Don’t waste your time.
I went through a ton of different options and found that the only two solid paths are BRU or PreRollPost. PreRollPost is more intuitive to use and based on an open-standard (LTFS). BRU is more full-featured, a bit more complex, and based on a proprietary standard. They cost the same. Both work very well. Both have high-level customers and advocates.
-Eric