Yes, I have done The Landmark Forum weekend. Very powerful and useful. It's similar to doing the 12 steps in a weekend. I remember reading someone saying that the Forum affected the same change in people in a weekend that it took him in 6 months of sponsoring people through the 12 steps.
They don't address powerlessness directly however I think the racket/strong suit distinction is pointing to the same thing. "You will always be racket (resentment) and strong suit ( personality/identifying with ego )." The distinction is to notice when you are that and then create a new way of being.
Where I'm stuck is where I think Landmark say you can create yourself and your life any way you want it to be, where as I don't want to be in charge of "creating" "my life" because there is only life creating and I want to get out of the way and let life guide me rather than me be in the driving seat. However I can see that this could just be a "story".