Thanks for the help with mine.
I don't think which one you give up matters that much. Marshall produces well even with average QBs (see Miami last two years) and has less competition for targets, especially in the end zone. Plus, Chicago has a tougher fight for their division and may need to play harder, longer, making him more valuable later, when Atlanta may decide to sit starters if they clinch earlier. On the other hand, White is about as reliable as they come and a great option on a great offense. (Of course, you should take Torrey Smith over Boldin.)
I think it's more important that you pull the trigger on this as soon as possible. Gore typically seems to wear down, so an upgrade like this at RB is awesome. I'd do it!
12 team, H2H, Standard Scoring (Starters in bold)
QB: P. Manning, Luck
WR: Julio Jones, Welker, Alexander, Hilton, Shorts
RB: Rice, Wilson, BJGE, LeShoure
DEF: DET, SD