A few thoughts...
Put a pin in the Henry breaking the record for about 3 years. It would likely take him 4 or 5 years to get there, maintaining his current level of production. That ain't easy. Possible? sure. But not entirely likely either.
Ah, the great RB debate.
Here's how I see it.
Barry was a better runner. If I was down by 5 on my own 10 with 3 seconds left on the clock; I'd find a way to get the ball into Barry's hands. He very well COULD take any play the distance, and make the defense look like children while doing it. Or he could get dropped for a loss.
Emmitt was a better RB. He did everything well. Run, block, catch...and he was rarely caught behind the LOS. Fourth and two at the 50, down by 4, 1:52 left in the game; hand it to Emmitt. Odds are, you'll get a new set of downs to work with. Or throw it, knowing that Emmitt WILL pick up that blitzing LB.
BUT....
If I could only pick ONE back for any team at any time, no question that my pick would be Jim Brown.
My RB Mount Rushmore is: Jim, Emmitt, Barry, and Walter.
There are a LOT of other guys in the conversation, but you simply cannot say NO to any of these four.