Absolutely not a problem to do that, as you'll see from this week and your example. It can be hard to watch because you have mixed feeling all day, but statistically a RB against a Def is not something to really worry about. RBs don't normally do that much damage as an individual, same with a WR. The only time I shy away from it is when it's my Def against my QB. A hot handed QB can torch you and that is a sick feeling or vice versa.
You can only lose so many points when your RB scores on you, but even then you will still gain points from your Defense when they sack the quarterback or force a turnover. So while its not the best situation, Its not going to hurt you very much at all.
You always start the players that you think will score you the most point regardless of them going against your def or someone elses....but I know its hard, I often have the same dilema, I just ask myself if I would start that player if the defense wasnt also on my team.
QB- Delhomme RB- Addai, Maroney, A. Green, A. Peterson (min), K. Jones, D. Williams, Foster WR- S. Smith, Fitzgerald, Stokley TE- V. Davis PK- Gould DEF- SD