I am not a member of EN, but I happen to know one of the founders (Rich) outside of triathlon. Rich is a very knowledgeable, no BS kinda guy. I think if anyone could tell you how to productively/effectively use 6-8 hours a week, it would be EN and Rich.
I am thinking of joining EN as I have talked with several members and they swear by the philosophy. They are limiting members, so if I don't get in I will definitely try the OS plans just based on the results of those I have talked to.