Sorry, i know what you're saying, and I don't mean to compare them as players. Right now Sproles is pound for pound our toughest guy though. I just don't see trading him. And I don't see him getting greedy, but we'll see.
I trade Merriman immediately for D-line talent. Key word TALENT. Not some no name douche like Travis Johnson or Ian Scott and a 5th round pick like AJ loves to do.
I'm not sure who to pick up but trade bait should be Davis, Sproles, Merriman, Whitehurst, Cromartie and Hart. From this group we should get a Pro-Bowl D-Lineman or O-Lineman. Another thought, as much as it bugs me, is to put Floyd or Nanee on the block as even trade material for the other needed lineman not filled in the first transaction listed above. Pay attention AJ. Your job depends on you adapting to your environment. Right now, your environment is a frying pan. Stand pat while the pan gets hotter or put the fire out before it's too late.