The other problem with choosing a back like that is that their "shelf-life" is usually much lower than any other position... outside of say a QB, who isn't going to make it as a starter.
CB's, offensive lineman, linebackers... you can coax a 10-12 year career out of a talented player.
But at RB? If the guy's talented he's getting the ball 20+ times a game, game in and game out and he's simply going to wear out much sooner so you're having to replace him much sooner.
The list of "bell cow" backs that missed significant chunks of this season is eye-opening.
I'm firmly in the camp of RBBC. Get good backs (not great) and give them the ball 10-12 times a game. If one gets hurt, then you can lean on the other for more carries.