No problem on the link. Here is a tip to avoid that darkness issue: Ensure that some type of power fractal (or image map shader) is plugged into the default shader's luminosity (though you may have done this - see below). Set the luminosity to "2" or so, though it could be set from 1 to 100 depending upon needs. I'm not sure what effect using the default shader exclusively will have as I've noticed color errors when using exclusive for colors in foliage. I can only assume these errors would translate. Lately, I've pretty much quit using the default shader, except for when I need to create luminosity values.
Keep in mind, with this GI technique, the background is what lights up most of the scene. You'll likely need to lower the sun's strength significantly, or even turn it off entirely (depending upon scene).
Darkness problem: I've also had problems with darkness on surfaces using the GI technique in random cases and I am not sure what causes this. I have a few ideas though. In the meantime, I have a clip file with a working version in case I can't get it working in the scene (which as stated, happens at random).
This technique is still a work in progress and I hope to have it perfected soon.
