This is solid for a 12 team PPR league.
I'm actually a little more concerned about your RBs than I am your WRs. You do have tons of talent at the RB position between Frank Gore, Jahvid Best, and Mark Ingram, but they come with asteriks. Gore has only played 16 games once in his 6 year career. Jahvid Best is a dynamic and explosive runner but his ability to stay healthy is a major question mark. Ingram is in a decently crowded New Orleans backfield. All signs are pointing to the fact that Ingram will get the majority of the carries, but I don't think Sean Payton would hesitate to switch that if Ingram stumbles early.
Roddy White will obviously be the anchor of your WRs. Percy Harvin, Anquan Boldin, and Mike Thomas are all in solid positions coming into 2011. Harvin has McNabb and a strong running game to help his chances while going into his third NFL season. Boldin has been working all off season with Joe Flacco, and Derrick Mason is now gone from Baltimore. This should allow Boldin to work the middle of the field more, so I expect a higher reception total compared to last year. Mike Thomas is the de facto WR1 in Jacksonville with MSW gone. Now, some of these could break the wrong way but you have a decent amount of talent and upside. Witten also will put up WR like numbers with high reception totals.
I'll admit your team does have a decent amount of risk between your RBs, Matt Stafford, and some unproven or under-performing WRs. With that being said, if a couple things go your way, your team will be very competitive.
Good luck in 2011