I doubt there's much you would miss if you chose the B9, but I highly suggest you either read rtings dot com review or watch it on youtube for details. They do compare the two. Here is what their written review said in summary "The LG B9 OLED and the LG C9 OLED have very similar performance. We expect this to be true once the BFI feature is fixed on our unit. Any other differences can be attributed to panel variance, including the slightly less aggressive ABL found on the B9." The review on youtube says that the abl flashing rarely happens. Remember that this was an issue on some plasmas a while back, most people rarely even noticed it and it was more of problem than what they're talking about with the B9.
You can call me Sheila.