This team is very strong for a 12 team PPR. I could see potentially moving Roethlisberger with anyone outside of your top 2 RBs (Jamaal Charles, Lesean McCoy) or top 3 WRs (Calvin Johnson, Larry Fitzgerald, Brandon Marshall) to try to upgrade your second flex spot. I'm not sure that this is something worth pursuing at this point in though. Moving Big Ben does come with some inherent risk. I assume that you went for your backup quarter back decently early because of Vick's injury liability. That plan has merit, and probably best left alone because you have enough talent to keep that depth.
Matthews could deliver what was expected of him last year should he remain healthy. Tolbert may vulture some TD's, and Ryan Matthews still is an injury risk, which makes me nervous, but Matthews could easily end up as a RB2. Amendola could likely shore up your 2nd flex spot if he fills the Welker role in the Josh McD offensive schemes of St. Louis. He could be catching 100 passes this year.
Your roster is unique because you are very deep at every single position, even QB and TE. You have several legitimate top tier options, so its not as if you need to trade that depth for studs.