Apparently, the info from Campy varies depending on who you talk to. Others report conflicting info from Campy USA. It's sad that those guys can't take a new lever apart and compare the old to the new. One poster was told that the spring pressure was increased by adding one more diaphragm spring. That would be a poor solution, since it's the detents that are different.
Sorry I can't help - I converted my 10 speed Centaur right shifter to 11 speed.