Quote - Forgive the omission........

You create a second sun opposite the first one with a tint about the same color as the Rendo blue, turn shadows off and set softness to 5. Makes great secondary light.

M

Mark, why would you set softness to 5 if shadows are turned off?  Softness only affects the edge of shadows.  If you turn off shadows for the light, then softness has no effect.

I agree with your idea however of using secondary diffuse light sources in a scene, particularly if characters are involved because it delievers a greater amount of specular light.  Indirect lighting even with boosted sky domes produce no specular light so you will need additional diffuse light sources in order to generate specular highlights.