I would do it. Brady is a huge upgrade over Romo and Marshall is good enough, especially with .5 PPR that I don't think you're downgrading too much giving up Rice.
You definitely need another good WR and Marshall is one of the best. The same with Brady at QB. But giving up Rice weakens your RB depth with Charles taking himself out of games, DMC learning the new zone-blocking scheme and struggling while doing so, and FJax sharing carries with Spiller on a team that will be 9 times out of 10 playing from behind and having to throw the ball 40-50 times a game.
I would suggest not doing this trade as is and send a counter with Charles and Jones along with Romo for Brady and Marshall. I can't see giving up Rice to upgrade your WR depth.
thanks for helping with mine. at first glance, i would say, yes, get brady. however, with mcfadden getting hurt today, it might be wise to hang onto rice. i think romo will put up good fantasy numbers the rest of the season too. if you can get a rb in return along with brady, then i'd do it.
PPR for QB, RB, WR; 1 pt. per 10 yds.; 6 pt. TD; 1 pt. per 15 return yds. QB: Stafford, Newton RB: Spiller, Sproles WR: VJax, Cobb TE: Myers W/R: Ridley Bench: McCoy, Mathews, Bryce Brown, Kaepernick, B. Powell, Gronkowski