This is not any proof, just my opinion. I believe any hard object is an obstacle, but I also believe that most broadhead tipsare so designed that the broadhead will deflect around the rib. But in doing so willloseenergy quicker and penetration while encountering a rib or other bone.

My analysis(like you want it) is smaller head equals less resistance. Bigger head equals more cutting ability with more resistance. Pros and cons of both.

Another opinion..........I don't believe its the modern compound itself that makes so much of a difference. Today's broadheads overall are much better than what we had to choose from years ago. Today's heads for the most part feature thicker blades, many are stainless steel, just better heads overall. Wish I had all of these broadhead choices whenI started bowhunting although shooting fingers at 60# with a slow bow I got many passthoughs.