tennisnoob, if you break a racquet you can have it repaired, assuming the damage isn't Safin-esque. Im not sure of the exact process, perhaps someone here who is a racquet stringer/technician could explain, but I think they cut out the broken area, insert a solid bridging piece and fuse them together. It's not something you see very often so don't know if they can do it with today's racquets. It wasn't very popular back in the day as it made the racquet heavier and totally threw out the balance. I guess the person had it done as they must have paid an arm and a leg for the Boron when they first got it. I seem to remember them going for over $400+ so that's reason enough.
I remember in the 80's being a hitting partner for an American guy, Eric Korita, who came out to Oz to play the summer circuit. He used the Boron so I got a chance to have a try of his frame and, I swear, if you think the PD is stiff you should have tried that thing. Surprisingly though, it actually had more 'feel' than I expected (which means it had almost none but thats more than I expected lol).