I agree and like the idea of letting top-challengers decide/adjust the base_score.
Maybe we could vote for some people, which are "representative", and ask them to discuss the scores in a more private scope. (I could make a forum board especially for representative challengers where this could be discussed)
When there are too less "representatives", we could also cast votes for each site, and let all users decide.
So i suggest the following challengers (in alphabetical order) to decide the base_scores:
alucardo, Inferno, quangntenemy, TheHiveMind, yachoor.
I surely forgot some people, so vote more here
Greets
Gizmore