From about 2000-2006, I worked very near an AD who sold both Lange and GO. I frequently looked at the two brands side by side. I never owned a GO but briefly considered getting a PanoRetroGraph. I always preferred Lange because GO, while very nice by itself, just felt much less well made next to the Lange. No part of the GO impressed me as much as Lange. But of course, that's reflected in the price difference.