-- Last Updated: Dec-13-12 7:17 PM EST --
Yep, to know more about what's going on, you'd want to do something like that. In the example I gave, it actually was the blade portion which was responsible for "too much flex" in the newer version of those two paddles, and the flex could be seen as well as felt when tested in that way. I suppose in the interest of keeping things simple, one could do the same test I suggested, once pushing against the tip of the blade, once pushing against the base of the blade (thus feeling shaft flex only), and maybe once halfway in-between. That's still pretty crude though, and like the bike-frame example I mentioned, none of it would mean much without the experience to make a good interpretation.
One could devise complex tests that really explain things properly, and in an ideal world the paddle manufacturers would publish the specs. One would still need to experience the use of various paddles to interpret the specs though. Further, in the case of wood paddles, like the cedar ones I mentioned, two "identical" paddles might well have a night-and-day difference between them.