On the Marshall Faulk argument, he retired when he became 33... That would mean another 4 years from LDT (They're not the same players ofcourse) if they'd turn out the same.
LDT seems to be going downhill though. He might post some big numbers, but his durability is catching up with him. He's only 150 carries away from being tied with Marshall and he isn't used as a receiver type as much as Faulk was. (Not taking anythign away from both of em)
I wouldn't like this move, I'd prefer to go with an unknown but pretty great speed back to complement Grant (Tatum Bell comes to mind, I think he's one of the most underrated players).