I have L/R, setup to datalog with EFI, or just the original right side when I'm driving. There is about a 200*F difference between the sides (left is colder). The left side is a BD, the right is a drilled stocker. I think the difference is the casting lug on the BD versus the drilled stocker means the probe is not quite long enough on the right side and not sitting in center of the manifold.
I'm a more info guy, but I would only do L/R.....unless I had a multi-channel datalogger, log style manifolds, and could do all 8.