The Wasserfall proved to be pretty much a complete failure as a SAM. The few German launches showed the difficulty of guiding it by optical radio control from the ground. The few US postwar launches showed how poor it was as a performer. The Germans might have been ahead in missiles but they were badly trailing in guidance and tracking systems. Sänger's "Silverbird" was another of those Nazi wet dream projects that just diverted resources from more useful and practical projects. As we now know some 60 or so years later a mostly aluminum with minimal stainless steel and no titanium in its skin or structure would never have stood up to the heat and stresses imposed by what Sänger was proposing. Just the lack of knowledge of the Earth's outer edge of the atmosphere and of near space flight alone doomed the project.