I am bumping this for posterity. I should make a page about it. Lots of great info in here.
Also: As someone asked earlier, has this comparison expanded to the JAPANESE PCE pads? What about NA Duo pads vs. JP Duo pads?
Yeah, I know it would be a lot of work to make such an extensive comparison. Especially because there were many production runs of the Japanese hardware/pads over the years. The same can't be said for any of the NA hardware.