ford 9 inch really?

So i am at a local car show the other night and this guy comes up and is looking at my Dart and tells me he is restoring an original 69 road runner. Cool then he tells me he is going to take out the 8 3/4 and install a Ford 9 inch because "they are the best rears and way stronger than an 8 3/4 or Dana". I said really?? i have no idea maybe thats true but i just dont see the point of putting another make rear in my car. Is the ford 9 inch really that much better? I am not a purist but i just dont get it. Maybe he should drop a big block chevy in place of the 440 because car craft said its a better engine...Can some one school me on the 9 inch...not that i would ever put one in my mopar but maybe i will understand better???