I think the matchup vs. STL qualifies as good enough to start both Jackson and Lynch. I also think LT/Sproles works, and even Hightower/James, although it doesnt have the overall potential of the BUF and SD combos because of the matchup. The nice thing about starting both backs in a juicy matchup is that you hedge against situations like your starting RB running the ball to the 3 on a long one, and then the back on your bench finishing the drive, or your RB yielding early in the 3rd and the guy on your bench getting 15 touches in the second half against a demoralized defense. You're basically betting on the 150+ yard multi TD rushing day from a winning team, and teams like ATL, JAX, OAK, and TEN set out to do that every week. With six teams on bye, some uncertainty in Philly, a three way committee in DEN, and BAL/PIT lining up as a low scoring war, some of these 7-12 "high value touch" RBs will get starts in deeper leagues. I could even imagine rolling with a Pittman/Young combo because of the scoring potential the Denver O offers this week.
On the subject of committees in general, I think it's pretty clear that TEN and JAX are fine running attacks to start both heads of when they have a good matchup. Seems like both RBs yield double digits (and more) when these teams get to execute their gameplan and impose their will on the opposing defense with 35+ carries to go around and each back softening up the D for the other as the game goes on. ATL has a similar personality and two high quality backs, but Norwood is more the compliment than the co-starter (like Jackson in BUF and Sproles in SD, at least while they aren't nursing LT's toe). CAR and MIA have the potential to go off in any given game, but it's harder to picture these teams jumping out to big leads with regularity, and they are also are not as strict slaves to the run as the first three. BAL is one to watch. They were basically using McGahee like a featured back before the shot to the eye, McClain is more like a finisher. So functionally they are like TEN and JAX when you see a good matchup, since they will also aim for 40 carries and both RBs have potential to score. In a tighter matchup, like this week vs PIT (even without Hampton), McClain is more the compliment than the co-starter. My hesitiation with pronouncing too many good matchups for them is the Flacco factor, teams will put 8 and 9 in the box if the D isnt giving them short fields and shutting down the opposition. I have similar concerns about OAK, and their D, while aggressive, doesn't look as good as BAL's D. ARI is evolving into something resembling JAX. They also have the will to run 35-40 times a game, so if the D and Warner continue to play well, they could be a committee worth starting in a lot of weeks.