downmixing to stereo

According to these posts on Hydrogenaudio forums, for downmixing 5.1 to stereo I should go with either
Lo = 1.0 * L + 0.7071 * C + 1.0 * Ls;
Ro = 1.0 * R + 0.7071 * C + 1.0 * Rs;
or
Lo = 1.0 * L + 0.5 * C + 1.0 * Ls;
Ro = 1.0 * R + 0.5 * C + 1.0 * Rs;

But I suppose in my case the C will have to be more since I want the commentary to be a bit louder.