in extreme use such as the paris-dakar, they fail readily. a Swede who I met in Dakar had 3 tanks for the 17 days of the rally and had to borrow someone elses to ride home! the rear tanks are fiddly and fragile plus a leak can run onto the exhaust and set the back of the bike - and rider - ablaze as Bertil found out riding back from Dakar.
I'd steer clear. the rest of their stuff is great
the IMS 27 litre stretches to 29 litre in the sun and you can use an 8 litre collapsible bladder for extra range. or fit that monster 45 litre tank!