Old and new Campy 10 speed compatibility

I can't even begin to get my head around why you think this would be the case? The spacing between 10-speed and 11-speed is different, so they must have different amounts of cable pull, otherwise you'd never get the gears to index properly.

As I understand it, all 10 speed components are compatible with one another. I've got 2010 Centaur levers, in the new shape, working with a 2006 (or maybe earlier) Centaur rear mech without any issues.

As AndyP said - it must be that the new 2011 10-speed rear mechs actuation is different. Before 2011, 10 speed has always been the same - like you have with your setup. The 'new shape' 'old logo' 2010 levers are the same as the previous 10-speed kit. But apparently different in pull to the 'new shape' 'new logo' 2011 levers.

I got this back from Campag themselves:

I confirm, it won’t work. With 2011 10S rear derailleur you must use 2011 10S Power Shift commands. The rest of the transmission can remain the same.

Cordiali Saluti/ Best Regards
Federico Fiori