D10 controller described near conflict event resulting from recently adopted procedures requiring tower to retain departures on their frequency to insure correct RNAV routing. Reporter voiced concern regarding the inability to establish timely communications to affect separation.

Narrative

Two Carriers were departing to the north. While already de-conflicting several DFW and DAL departures; Air Carrier Y checked in out of three thousand five hundred climbing to five thousand. I RADAR identified the B737 and instructed the aircraft to fly runway heading and climb to eight thousand feet. The runway heading of 310 off of DAL would have de-conflicted the B737 with the DFW departure; an E135 just north of the airport. Air Carrier X then checked in six miles north of DFW out of five thousand six hundred climbing to ten thousand. I RADAR identified the Embrear and amended his altitude to seven thousand in order to de-conflict him with other departure traffic in his path. I observed Air Carrier Y in a turn northbound and amended the B737 to maintain 6000 to de-conflict him with the Embrear Air Carrier X. Several minutes later Air Carrier Y advised me that he went through the assigned altitude of 6000 feet and I acknowledged his transmission. Recommendation; due to the current requirements that the Tower maintain contact with departures at DFW until established on the appropriate RNAV routes; aircraft are continuously contacting the Departure Controllers four to five miles off the departure end of the runway sometimes climbing out of five to six thousand feet depending on the current weather/wind conditions. Air Carrier X did not establish radio communications until he was already six miles north of the departure airport and out of five thousand six hundred feet. Therefore I was not in contact with him before he was out of the altitude that DAL (Dallas Love Field) jets are assigned to procedurally separate them from the DFW Departures. Additionally; every effort should have been made to ensure that communications transfer was transferred as soon as possible to provide ample opportunity for the issuance of traffic and radar identification of both aircraft. The practice of retaining radio communications to establish that each aircraft is capturing the appropriate RNAV route is creating more hazard than if they were switched to the appropriate departure controller who is responsible for separating these aircraft.