As far as knockdown power..
It's the difference between poking an animal in the shoulder with a 110gr bullet and having it go a long distance, and poking same animal with a 200gr bullet going a high rate of speed and having it drop right there.
Night/Day difference between hitting an animal with a 338rum and a 30-06. I've done it a bunch of times, and the "knockdown" power of the RUM is rather impressive.
