It all goes back to what is important to you.
I agree that Barry Sanders is the most explosive RB in history. Although Gayle Sayers was as explosive, just too short a career. The "complaint" about Sanders was the number of negative plays that he always had that offset the big plays.
Comparing MVP makes it dependent on outside factors. A better season overshadowed by someone else's great season, etc.
Often stats are biased based on what your team focuses on.
Walter Payton played most of his career being the main player on a terrible team.
Same with OJ Simpson.
Emmet Smith played on a team with a great offensive line and a passing game that was based on running the ball and play action. He was a major factor in the offense. He also played in the overlap of offensive explosion that started in the 80's and continues to grow, and the dependence on RB, which has decreased since the late 90's as RB moved somewhat towards Marshall Faulk and Alvin Kamara types. You still had traditional RB but they have steadily decreased as pass catching RB moved to the forefront. They still exist, but they have to share the backfield and even take 2nd place behind the pass catchers. Look at Mark Ingrams career. Other than DH, the last notable (as in on the top 20 in stats) trad running backs are Jerome Bettis and Adrian Peterson. (depending on how consider Frank Gore)
I think in terms of a traditional RB, DH will very possibly end up being among the best ever. I would consider him that now, but stats will likely be a problem.
He currently has 12,243 rushing yards and if he plays decent for two more years, he should end up 5th all time, assuming he gets above 15,000 yds. To get to 1st, he needs over 6,000yds to pass Emmet S.
He has 113 rushing TD and with just 10 more, he would tie for 3rd with Marcus Allen. But he needs 22 beyond that to get to 2nd and LT, and 20 more beyond that to catch ES.
So at this point, its going to be about time, how much longer can he play, and at what level. 6 more years of decent (from his standard) play would get him there, but that is a LONG time for a RB.