Here are the facts. Zinn is wrong about the cable pulls of Campy 10 and SRAM 10 being the same. SRAM pulls a uniform 3mm per shift. Campy pulls 2.5mm five times 3mm twice and 3.5mm twice. The total pull divided by 9 averages just over 2.8mm. After only 5 pulls, a SRAM shifter would pull enough cable to make 6 shifts on a Campy 10 drivetrain. That's a huge difference.

It just so happens that Shimano 8 shifters average a nearly identical 2.8mm of pull per shift, but they are also nonuniform, so a SRAM shifter would greatly overshift on the first several pulls. A Campy 10 shifter would probably work a whole lot better than SRAM 10, with Shimano 8.