I've been let down all year as well with Edgerrin. In fact, I missed out on a ton of points from James Stewart this past week because I feel obligated to start Edgerrin every week. However, I do continue to believe that you have to keep him no matter what he has (hasn't) been doing. His potential is too great especially with his receiving ability combined with his rushing potential.
As far as Portis and Henry... I'd consider starting Henry in place of Edgerrin if the matchup is right. My remaining RB's are Jamal Lewis, James Stewart, and Lamar Smith. None of them are consistent. I guess that's probably why I'm 3-4 so far