Hi
I took one of the 12ltr bladders on a trip to Birdsville in outback Queensland. It actually wouldn't hold much more than 11ltrs and is quite tricky to refuel the bike.
It comes with a screw on filler tube but this does not quite fit through the aperture in the screen inside the XT tank. I will find a smalle tube to fit on to it next time.
The bladder it self sat very well on the pillion seat strapped to the luggage.
I'd include a picture if someone can tell me how!

Ed