Hard to know without seeing your lineup but not unless you really need a WR. Warner > Hass. I don't think Smith is nearly enough value for what you are giving up.
12 Team League. We start 2 QBs and get .5 PPR, otherwise standard scoring
QBs: Stafford, Fitzpatrick, Collins
RBs: Charles, Mendenhall, Best, Starks, Carter, Karim
WRs: D. Jackson, Marshall, S. Smith, Green,
TE: Hernandez, Cook