I bought this FastBag and had it painted metallic black for a Kawa GTR1400, which I sold before I could use the FastBag even once
And it happens to be a perfect match for the XT's Pearl Cosmic Black color.
This is a pretty clever solution if you ride solo and don't want to use (or do not have) side bags. It consists of a sturdy plastic compound frame and an expanding concertina-type nylon bag. The shell, which you can lock, is made of composite material - no polycarbonate. The FastBag is secured to the bike's frame through 4 tie-down straps, has a velcroed overlapping flap inside that makes it waterproof and comes with an inner nylon bag to boot.
Once you remove it from the bike, you can carry it like a backpack. There's a soft nylon pouch velcroed to the flat forward side of the shell which used to contain a small first aid kit. If you install the FastBag close enough to the pilot, the pouch will also serve as a backrest of sorts.
This item is virtually new and I'm selling it because my Special Edition XT has more bags than I'll ever need...
(3 SW-Motech hard bags that came with it, an Axio tank bag and a Nelson-Rigg soft case).
I'm asking Eur 150 plus shipping. (It needs to be packed properly, so the shipping costs may run up to 20-25% of the item's price even within Europe)
More info on the FastBag here: http://fastbagusa.com/