I believe your premise is incorrect, regardless of your vacillation.
The Yonge line will not actually be "relieved" by a DRL, although Yonge station will somewhat be. The problem with the Yonge line during morning rush hour is that south of St Clair, trains are already operating at full capacity and are virtually unbordable at times.
Flash forward to 2020 and increased intensification on St Clair and Eglinton. Flash further forward to 2025 the possibility of an extended Yonge line bringing on even more riders. The DRL will siphon off east end riders from Yonge-Bloor station only, and if intensification continues in the west end of the city, there will still be the crowding problems at that station which we have now, and trains will potentially be at capacity south of Eglinton.
The DRL might arguably be best thought of as a "Danforth Relief Line", especially if built out to Coxwell or Woodbine. But it still won't relieve ovecrowding on the Yonge Line that originates north of St Clair. At the same time, if downtown intensification south of Bloor continues, realistically these people might very well not be able to board the Yonge line at all, depending on their destination.
Unfortunately the DRL won't relieve any of this.
So in this case, a close parallel route to the Yonge Line -- even closer than the University line -- likely stands the most reasonable prospect of providing relief and absorbing riders from the Yonge Line.