Winpattern: I too use the Koll balancer and heretofore have meticulously balanced cord and span CG as well as see saw weight matching (the Koll is truly a great little invention). I have never had any vibration issues doing it this way, and as you can see, this is clearly the conventional wisdom. To answer your question, no. You can get a set of blades to balance against one another on the see saw, while still having very different spanwise CGs (and even different weights). The reason is, a blade with its mass concentrated at the tip will have more leverage (moment) on the see saw than a blade of the same weight with its mass concentrated at the root. Thus, two blades of the same weight will not balance on the see saw unless their CGs are identical. Similarly, blades of different weights may well balance on the see saw if their CGs are such that the lighter blade has more of its mass concentrated at the tip, relative to the heavier blade.

Thus, the "correct" method, is to match the spanwise CGs first, then see saw balance, adding weight to the light blade AT THE CG. Then you will end up with blades that are the same weight AND have the same spanwise CGs. Whew!