Search Volume is the Best Indicator of Satisfaction

Consider this article over at SEOMoz by Rand Fishkin:

SEOmoz | Yahoo! Is the Most Fulfilling Search Engine?

Rand acknowledges Compete.com's recent findings that say Yahoo! is the most successful major search engine at getting users to click on a result - in other words, Yahoo! SERPs have the highest CTR. However, Rand extrapolates from this that Yahoo! users are the most satisfied users. I don't know if this is the case - just because Yahoo! has a higher CTR on their search results, I don't know if that means Yahoo! users are more satisfied than Google users.

By contrast, I would look at reports such as this one and extrapolate that, since Google's market share is so large, that means Google is so satisfying that it gets everyone's search attempts - even the ones where people don't think they're going to find anything.

Obviously, there are some differences between SERPs on Google and Yahoo. At least, 7 of the top 10 sites will often be the same, though they may not be in the same order. These differences may be what gives Google its edge in market share.

I would like to see some data on searches per user. I know this would be hard to compile, but I think that would take us closer to knowing which SE is actually more satisfying. If a user identifies one SE as more successful, my guess is that the main indicator would be the return visit. And, based on Google's proven ability to steadily keep its market share up, I think the right assumption would be that Google is most satisfactory.