It has happened to a BA classic coming out of somewhere in Canada (Montreal or Toronto I think). It hit a flock of geese and had to return. Can't remember the exact story, but was an interesting read, and I'm sure someone can give more detail.
The 400 has a lot more performance than the classic, but out of Canada it would have been at a relatively low weight so would have performed in a similar way to a 400 at 'normal' weights.