lmsco wrote a review of Mammut Vader Alpine Belay Device on May 17, 2013
The belay device operates almost identically to my Petzl Reverso. Other than the shape, I don't feel a difference. But just like others here, I also encountered a torn plastic keeper loop after a normal rappel. Mammut's customer service told me it was user error, and I was racking my brain trying to figure out what I might have done differently on that rap, so it's good to see some reassurance that it isn't me! They did still offer to replace the device, however, and were quick with their reply.