Questions
C. Newton or Sam Bradford or Weeden?
Cam is up against tough Bears defense but runs the ball a ton, which is great. My hesitation is obviously the defense but last time I benched Cam against a tough defense was Atlanta and he had 20+ points.Bradford is up against Patriots secondary.
Cam Newton 
Sam Bradford 
Brandon Weeden
Is Weeden available in your league? If so, I'd probably rank him SLIGHTLY higher than Bradford this week. Yes, the Pats secondary is awful, but if I'm not mistaken, the London games have been low scoring in the past. I can see NE keeping the ball on the ground (especially since I just traded Ridley today), which keeps the Rams offense on the sideline.
Weeden also faces a bad pass defense in a possible shootout, and his RBs are hurt (both TRich and Hardesty). They are throwing. I only put Weeden slightly ahead of Bradford, so if Weeden's not available, or you prefer Bradford, then go with Bradford (its your team).
But to answer your question, yes, I would bench Cam for waiver wire fodder this week. I'm doing it myself (its sad that Rivers has become waiver wire fodder these days)