I'm with #alcjphil on this, until someone test a set, like Zinn/Arts, would take it initially that the new design isn't compatible with the old stuff.

Would clarify by contacting my countries Shimano main service center and asking them (at least in the UK, they will talk the the general public, and not just LBS's about things like this), even if the answer is the official line from Shimano, not what you can do with it with some ingenuity/3rd party mods.