IDK. With RGIII under center I don't feel too confident beating anyone. My guess is Lamar practices tomorrow and they try to win the game with a lot of ground game from the RBs. But you need Lamar's run and pass ability to gain an advantage on the ground and RGIII offers none of that.
I think RG3 hasn't looked particularly great in relief of games, which is partly him, and partly because the Ravens have throttled way down at that point. I think he looked good in the prior preseason games (obviously not this year) and I think he still has something left. Not Jackson clearly, but good enough to win with (especially this surrounding cast, against the Bengals).
You don't want to lose against Cincinnati, and no Jackson would make that a possibility... but I still think you win, and the larger point is the Raven can't win anything that matters if Jackson isn't available and right. So I'm giving him the week off if that increases the chances of him being right going forward.