I was under the impression the D402 carried the EliteII as sort of a bull$hit secondary designation.
Local conditions like temperature and pavement type probably make more of a difference then tire brand as long as you stay with the good ones if riding style and weight stays the same.
We tend to get good mileage out of them as the roads here generally are exceptionally good and not as abrasive as in some other places.
The new highways are covered with some sort of covering that has old ground up tires mixed in, riding on this stuff is like riding on a cloud. They say that eventually all the highways in the state will be covered with it. Maybe our mileage will go up.