Re: 12 round limit, saved lives?
I'd say no.
In most cases where there is a ring death, it has been because of incompetence on the part of the relevant control board or ringside officials on some level. Corner men can field some of the blame too.
Clipping 15 rounders to 12 rounders has made next to no difference as far as safety is concerned, in my eyes. The logical conclusion, if the number of rounds was the main determining factor in fighter safety, would be to make championship fights 6 rounds, or 4 rounds...which is ridiculous.
Sure, in a long fight there may be more potential for permanent injury or death, but it's up to the officials at ringside to protect the fighters properly, and the duty of the control boards to give the fighters a thorough medical beforehand.