I always enjoy posts that contain more than 1 persons opinion.

It seems to me though that there is a consensus that it works, but variations on why or how it works.

In conclusion I would say that either direct sales or brand building both work. It's a case of knowing your audience. If you can understand and really get to know your audience and their problems, you can devise an email that will really help them out. And then your on to a winner, whether it's direct sales or free info or other.