I like Duke Johnson myself - he's not a back you can give 20 carries a game too, but 10-15 touches - catching the ball out of the backfield and his ability to take 1 to the house should be valued. Him, Ivory and Powell would make a great 3 back combination - all w/ different skill-sets. Not all that sure about Duke Johnson and pass-protection, but we have Powell for that.
I don't disagree on Coleman not being a good east-west guy at all. That's true. He's definitely a one cut runner and that's what I prefer in my backs. Especially one paired up with Ivory, one cut and GO. I'll take a closer look at Johnson, your scouting report seems good to me, and yes this team could really use a pass catcher out the backfield
Wasn't too long ago teams carried one tail back and gave him the rock 25 times a game, every game. Curtis Martin comes to mind. Then the 'tandem' backfield came into vogue. Bruiser between the numbers and a scat back to own the edges. Now teams need a trifecta to run the ball? What's this world coming to? Next you'll try telling me "It's a passing league".