Thanks for the link, JHess! Pretty neat video, although it shows a current "Double Servo Panta" (is that what they called it when they went to a slant parallelogram?) model, while I'm more interested in their original "Servo Panta" mechanism, pre-slant-par (think original 600, or Arabesque).

Jim, what you wrote above echoes my own understanding as well. So either I'm not crazy, or you and I both are. By the way, I always thought the adjustable parallelogram of the first-gen Chorus derailleur was quite slick, and I've always wondered why they (or other manufacturers) didn't pursue that further.

Still interested in hearing from a few more people!