I'm surprised I haven't seen it mentioned but using the balloon as the point of impact, means any ship can do it and come away with repairable rather than permanent damage not just the Pyra.
Direct impact damage does have modifiers against all components- at a constant speed of collision:
The balloon will take 1.8x more damage,
The hull will take 1.2x more damage,
The armor will take 0.8x less damage,
The guns and engines will take 0.6x less damage.
While it is a smart choice to use a balloon instead of the armor in order to ram, it is important to remember that this maneuver shouldn't be used like a Swiss Army knife- in all situations. Generally, I always expect my balloon to go down after a balloon ram. While the ram does do damage... because that balloon goes down, I will lose gun arcs on my ship, which would allow both ships to repair back to normal.
I keep impact damage in mind when I ram larger-armored ships, like the Galleon and the Junker. One huge ram will pop them and put us in a better tactical position.