Fantasy Football Question: Should I drop... and pick up...?

Alright. I have Steve Smith (NYG), Reggie Wayne, Marques Colston, Wes Welker and Austin Collie. The guy im up against this week has an empty slot for WR and Steve on is available as a FA. Should I drop Austin Collie for on? I want to do it because on is supposed to have a big game... and i want to keep him from the other guy, and he usually adds/drops on Saturday so I can steal on now. My only concern is somebody picking up Collie after I drop him, and on losing playing time to Boldin down the road. I just dont have anybody else to drop other than Collie. I dont want to lose Indy or Denver's D. I cant give up Gore, Lynch, Benson, DeAngelo, Cooley, Owen Daniels, or Flacco and I change my kicker every week. Collie, i think... is the guy i can lose. What do you think?