I'm impressed by the complexity of your analysis, but I'd like to try a simpler and more intuitive approach when judging skill challenges.
First of all, lets assume that the PCs are supposed to be winning the skill challenges, just like they're supposed to be winning most of the combat...
The first community Points of Light wiki site I set up seems to be suffering from severe techinical difficulties, so I've moved this project to a new free host.
Premilinary world maps have been added to the project now. Join now to add your content. Go to: http://taezaria.wikispaces.com/...
I have set up a wiki to serve as a base for a new community-based PoL campaign setting. Feel free to join this community and help create an entire PoL world.
Check out: editthis.info/pol