Most SEO experiments are a complete waste of time. SEOs tend to design extremely flawed experiments.
What the majority of experienced SEOs have to offer is a base set of experiences and networks of associates whom they can draw upon for advice and/or assistance. Nowhere in any of that will you find x-ray vision-like capability of analyzing complex search engine algorithms.
In fact, the search engines are only part of the picture. What people do with their Web sites and what people search for (as well as how they search) are factors that only make an already complex process even more complex.
You can certainly place your blind faith in an opinion survey but even if we assume for the sake of discussion that the low-level consensus the survey indicates somehow approaches an accurate depiction of Google's search algorithm, that collective opinion will be obsolete in about 6 months. Google adjusts its algorithm about 10 times a week, or so they claim. Those are all pretty small changes, but they add up over time.
Google is a very different search engine from what it was in October 2007.
An opinion survey represents a snapshot in time, which is nothing anyone should be basing their SEO strategies and principles on.