Gybing Plates

If I have understood correctly.

A gybing board does not have magical properties that make a board "climb" to windward and there is no such thing as something for nothing. The most significant benefit is to allow the boat to track straight through the water for most efficient use of hull shape.

If the above is right, given that hull alignment is top effect can I ask a couple of simple minded questions.

Would a heavily chined hull shape benefit more than a round dish?

Is the benefit greater in displacement mode, as when planing there is less hull in the water and what is would most likely be pretty flat anyway?

Does the fact that gybing boards are big in Five Oh's (round and planing hulls) mean the above questions are total tosh or Five Oh's simply love tech?

Dan. Another simplistic question please. 

For a boat with a fixed board does it generally follow that when beating speed is your friend by generating greater power from the board at a lower angle of attack = less yaw of the hull. Pinching is not good if it means less speed and therefore a greater angle of attack needed to generate the power to oppose the rig force = more drag from hull yaw. 

Is pinching for height nearly a optical illusion? When in fact the actual track is probably the same or even worse.