Just commenting on your last paragraph:
Bumping the minimum level from 5 to 6 or 7 is only a temporary solution. PM is like a breeding pit when it comes to XP.
As the userbase is always expanding, more and more people will be casting their votes on posts (either positive or negative).
This will eventually result in more people with a higher level, who themselves have more votes to spend on each level they go up and thus will up the level of others etc etc ..

Perhaps one could modify this genetic programming post to describe a userbase of 100 Monks that regularly post and vote, then see how long it would take before one ends up with 30 allmighty saints, und 70 humble initiates :)

jorg