Thoughts on this new way of adding storage?

No way I could get a leg over, or around, that monster bag.
What you are struggling with is why I still ride my R3R around the country.
 
I think it's a good option if you need more than the tailpack + a backpack can carry (how I spend a few days away), but like others have said, I'd PPF the painted tailsection to protect the paint, and I'd never waste time mounting it on the rack as it has 3kg weight limit. Like Jagster said, it's just cast ally held in with 4 bolts to the also cast backrest. Several pics here of it snapping off under load.

Of course, not pillion friendly, so if that's important then it's back to panniers or build-your-own steel backrest mount and rack, but I suspect you'd then run into subframe mounting strength issues,,,
 
This is my big bug bear with R3’s, you can’t really comfortably tour two up! I took the Mrs to look when they first came out, she took one look and said not a hope! Rear seat too small, back rest again too small and foot rests too high. And as mentioned the rack, too small, fragile and brittle.
I feel Triumph are missing out on sales, I know a couple of folk who’d have had one, but for those things!!