I have an S1, which I have had for about 2 1/2 years. I recently replaced the original bag fixing straps ( the bag would rotate on the trolley sometimes) with their new bungee and hook type of fixing. My T130 never moves from the moment I hook the straps together now  regardless of terrain the trolley is given. I would say that with these new bag straps on the trolley make the need for a bag that locks on the base plate is redundant.