On the logic of the point in question, I'd have to say yes, loud pipes do save lives. I've heard many a loud bike coming up behind, and approaching from all angles. I'm sure it makes drivers aware there's a bike nearby and they look for it. Some drivers, anyway. That's got to be a good thing.
My accident in which I lost my leg happened cause the driver just didn't know I was there. That, and because she was somewhat senile, I think.
That being said, I like a quiet ride. Tried the straight, loud pipe when I was a teenager trying to be macho and had enough of it after a couple months.
Now, THAT being said, after a few close calls recently, I'm thinking half seriously about opening up my muffler some just for the awareness factor.