I ran the cable in the shifter and then firmly secured the other end in a bench vice...In order to make a clean measurement, I removed the barrel adjuster...I pulled the cable tight and marked where it entered the shifter with electrical tape...I then shifted through seven clicks and used calipers to measure the amount of cable pulled: 21mm...I divided that number by 7 which results in 3mm per click...Since I was sinking a few hundred bucks into the purchase, I repeated the test three times to be sure and came up with the exact same result every time...Though I've never met the man, Lennard Zinn seems to be a pretty precise fellow so I'm taking him at his word...
It's actually not an upgrade path, I'm building up a brand new bike with all new parts (except for the old shimano rear derailleur)...I'm just not impressed with the durability of 9 and 10 speed drivetrains...