I'm not sure if they have tried a crossbow on the breastplate or brigandine. I do know Tod Cutler has, in the past, created a crossbow specifically to mimic the longbow Joe Gibbs shoots. So, my bet would be on it being pretty similar. At the end of the day, armor really did work and worked well. There is a reason it stuck around so long in history. Even to the point of firearms showing up. Some armor could stop early muskets.