It appears as if the common worries are:
A) People worried they are a higher level that their level is not representative of their knowledge (we won't get into the whole what you know vs. what you deserve thing)
B) People who have so much experience that others fear they will leave from a lack of stimulation/challenge
What I would propose is the creation of a Perl Monks Aptitude Test OPTIONALLY run by those who would fall into catagory B. Their advanced knowledged more then qualifies them to come up with the appropriate catagories. They have also been answering questions for lower levels (basically most everbody) that with some thought and research they could probably define "average knowledge" of any given level.
This test could OPTIONALLY be taken and be made OPTIONALLY viewable to the public from your home node.
This way, people who feel the need to display their worth strictly in programming theory and perl syntax can have that option. A PERLish counting coup so to speak.
A well thought out test would not only be challenging to create, fine tune, and score, but it would also appease those who feel they don't belong in the level they are at.
Just keep in mind the goal is maximum amount of fun and community involvement.
Thanks for your time,