Definitely some variant of the DW6 then; nice pauses @uina. I went ahead and laid out a very rough draft in Linkage, but without a clear side view it's fairly difficult to get any sort of accuracy, and I don't know if we'll ever get a clear look at the tiny linkage driving the chainstay. The finer characteristics are very sensitive to small link adjustments, so again take this with a heavy grain of salt (changing the orientation of the two short links for anti-squat could make the end of the leverage curve regressive, linear, or progressive; I went with...