the "cash back" is nice, but I'm more talking about finding the right house (more important I think!)

With redfin you can (and, are required) to do your own discovery: finding the house you think are potential candidates and touring them. Redfin has an associate go with you to the houses you are interested in to show you around/answer questions.

For me, it took about 4 house tours before I figured out the house type I was aiming for. After that, then next 10 or so tours was just trying to find a house that offered the best bang for the buck (based on what I was looking for)

Ultimately, if you have the time available to do this kind of footwork, Redfin offers you "choice" that you won't get from an agent. However if you are time constrained or not willing to put in 40 hours over a few months to find your perfect house, then a traditional agent will be better.

Also keep in mind that I'm in the Seattle area, which is Redfin (and Zillow's) hometown, and as per the original article, maybe in other regions redfin's listings may not be as comprehensive?