I had a conversation with TRP who was informed about Ritterview's failure. FYI, they were here in my home town Boulder for the big Cyclo-cross races.
In case you find yourself in this discussion with TRP, it was suggested the reason Ritterview's Spyre SL arm failure was unique to the case where the front brake was not engaged and was on a tandem. I argued that one typically uses the rear brake alone for this sort of descent, even when the front brake is available. And in any case, the pulling force induced on the SL arm with a brake lever is based on the brake levers ability, not based on how many brakes, 1, 2, 3 or a dozen, happen to be on the bike, nor is the force from your brake levers affected by how much the bike weights. There is no greater force available from your brake levers onto the brake arm, when the weight of the bike is increased. That would be a SWEET brake lever if it knew how much the bike weighted and gave you more braking power!