I would much rather base my puppy selection on the above observations over several weeks, than one test or maybe 2 conducted at most twice. In my experience of evaluating puppies, the breeder observations usually held true throughout the life of the dog, whereas a puppy test is a maybe. As I said once before, if I were looking for a puppy to do agility with, the most important factors to me are soundness of the parents physically and mentally. Everything else can be taught, but a natural jumper is more born than trained. Training and trialing require mental concentration and a steady dog.
Sound temperaments are much easier to deal with spooks, or aggressiveness.
The study mentioned is not the first that indicated that the traditional puppy testing was not a good predictor of adult temperament. It simply confirms results from earlier studies, using a larger sample size. The military is working on an even more extensive puppy testing program for their own dogs, trying to improve predictability, but their results have yet to be released. Last update I heard a few years ago indicated that they were looking at over 20 different traits. Too much can happen between testing and adulthood, which can bring out both the best and the worst in a dog.