TRD,
enjoy the big boobages while you're young. Gravity is a bitch. I'm wearing a friggin' scaffolding at the moment. And I would with a lot of men in a male dominated industry. So I have ot be extra careful in not flaunting them.
The ONLY time I appreciated them was when I had a psycho horse. As I was trying to get on Psycho Spot, he spooked. I was half on, half off. He kept going and I was mounting him in our gravel courtyard. Needless to say, I couldn't stop him and couldn't get all the way on him. I hit the dirt face first. Luckily, the honkers broke the fall first and I landed on them rather than directly onto my face.
Yup, that was the only time I appreciated large boobs. Otherwise, they really play a factor in x-c. I have to lean back further on drops than a lighter person and if I lean forward too much, it affects my horse more than other people.

Average, for horses with some experience at this level