1.DD will not help DP passengers. It will help those who want to travel reserved.
2.During Weekends, DP passengers don't spare the AC coaches too in 14659 (personally experienced things)
3.I support if Non-AC DD coaches are introduced to help those passengers who want to travel in less fare but reserved. and As DD has limited stops DP passengers would not board it.
4....
more... There are huge crowd of people wanting to take Volvo from Delhi to Jaipur in the evening time just after office hours. (especially from Gurgaon). When I used to work in Delhi, I preferred Rajdhani (12958) to go to Jaipur over Volvo's as I got food and sleeper berth at the same price, Although as Jaipur had only a Quota of 8 Seats in 3AC in 12958, one has to plan well in advance.
Give some time to the train, and it will be a definite hit.