That's an interesting point about Kanigher and Kubert moonlighting on the Superhero side. This time frame matchs up with Marvel's hiring of Buscema, Colan, and even Gil Kane.
I wonder if more work was promised to damp down defections, or was the workload across the D.C. line being shaken by Marvel's moves.
James Friel or Alan Ross would have good insight on this.