First off, let me say that I think we should honor or retire Dalton's number (whichever, I don't care). He is up there with the greats at TCU and won us a Rose Bowl while being the all-time winningest QB in our history. He led us to the program's greatest heights since the 30's.
That being said, measuring LT's career against Dalton's career based on the team's accomplishments during their time in school, is not fair to LT. You have to look at the setting they stepped into and think about who could have done what they did, considering their surroundings. How many RBs in the history of football could have come into TCU and carried the team on their back in the fashion that LT did? How many could have run for 406 against UTEP, how many could have led the nation in rushing for however many years, how many could have taken a 1-win team to almost reaching a BCS game? I would say that it's not very many. He was (is) a truly elite RB, one of the best that the world has ever seen. The fact that we didn't win the Rose Bowl while he was @ TCU wasn't something that he had any type of control over.
Now, what Dalton did in his career at TCU was also very very impressive, but I'm not ready to say that only he and a couple other QBs in the history of football could have pulled it off. Dalton inherited a much better situation at TCU than LT did, there is so much more talent on this team from top to bottom than there was in the late 90's.