If this counts as a thread hijack, my apologies and please ignore me, but it strikes me that people who have Henry might know something about/be interested in other backups with better shots at getting serious PT.
I currently have McGahee on my bench, and am just about to drop him. Henry seems to have a lock on the job, and unless he gets hurt or drastically starts sucking, I don't see McGahee being a very useful fantasy back this season.
Perhaps a better option would be to see if Tatum Bell is available. Griffin's gotten a lot of early hype, and with that it's possible that people in your league might have lost sight of the fact that Griffin's a more precarious start than Henry (what with the gimpy ankle, etc.).
Any thoughts from people on the relative value of Bell and McGahee? Would it be worth making the switch given Henry's hold on the Bills job?