But you are not really gaining anything either. Try to imagine a bell shaped curve. The Y axis is draw weight and the X axis is draw length. A smoother drawing cam has a narrower bell shape since you only hit the peak weight for a very short duration of the draw cycle. Lets just say 4 inches for example. The entire rest of the powerstroke from brace to full draw is spent increasing to that peak weight and decreasing from the peak weight into the valley.

A harder drawing cam maintains its peak weight over a greater distance of the draw cycle. Lets say 10-12 inches. In other words you are pulling that peak weight for a greater percentage of distance from brace back to full draw. That is where the extra speed of a harder drawing cam generally comes from.

So, with that 55 lber you mentioned (assuming a hard cam) you are holding that peak 55 lbs for (my suggested) 10-12 inches of the draw cycle. With the softer cam and a 65 lb draw weight you are holding that peak 65 lbs for only (my suggested) 4 inches of the draw cycle. As I mentioned, the transition to that 65 lb peak weight and from it into the valley might make it feel a bit easier than the 55 lb draw weight and then again it might not. It all depends on the two individual bows being compared.