"Planking imbalances on lower level vessels.
We want to compact the planking integrity on unrated vessels bringing them closer to each other. This will increase variability and improve ship choices for shallow water combat. The difference in hp and survivability between a Navy brig-sloop and a privateer should not be as strong as it is now (almost 2.5x)."
Not sure I agree with this, and here is why. The brig is a much larger target and far easier to hit then a privateer, cutter, or pickle. Even larger then the Snow which packs more guns and handles weathering into the wind better. While the Brig and Navy brig only 2-3 more guns of the same poundage for long guns (brig-navybrig). If you bring them too close to each other in terms of structure and armor then the Brig and Navybrig will end up lame ducks. The Privateer, Pickle, and Cutter all get effective structure and armor in that even well aimed shot will have several from a volley that will pass over the gunwale.
Perhaps introducing 8lber medium guns for the Brigs will make closing the gap more viable and not swinging the advantage the other way completely.