Don't give up Gore. Gore and Rodgers can keep in contention almost every week.
But your WRs are pretty weak, so trading S Jax for a lesser RB and a WR is not a terrible idea. Not sure I like DWill and Marshall all that much though. Think you could get anyone better?
Might be better to hold off and hope one of your lesser RBs starts scoring more than people think they will. Maybe Spiller or Starks will get a bunch of points in one of the first weeks and you can trade them instead.
When in doubt, I always stick with better RBs. WRs are too hit and miss for me. Even the good ones still have weeks where they get almost no points. A good QB and two good RBs will win you games, as long as get lucky with WRs every once in a while.