Thanks Mike, I like how you're expanding the 'perceptive scope' - sorry, I just couldn't think how else to word it :~P - by suggesting ways it might work.
Using karma points would work for some things, but for others it would need to be more specific, e.g. a member who has submitted 20 original and 'suitable' photos to the community gallery may earn a promotion to Photographer, with the same authority to self-publish (at least with regards to images) as the Author role. Of course this type of promotion could only be awarded based on a specific type of activity.
Perhaps there's scope here for an A4WP (nod to Mike) add-on to act as intermediary between A4WP and a user-role plugin (e.g. Membership+, etc...), so that when an achievement is triggered, by award or event, it will check to see if the users role needs to be added to|amended.
I fully accept that this might be an unreasonable feature expectation, but I'm a concepts guy, so it's in my remit to stretch, push and challenge.
However, I think adding this kind of functionality - i.e. automatically adjusting the scope of a users role based upon their actual activity - has huge potential for enhancing a dynamic, community based website.
This could even be further extended with the possible future feature of users|members being able to award each other 'helping' points (or, whatever) and possibly elevating someone to a Moderator role by community consensus - for example.
Just thoughts I'm throwing out into the ether, but with a sense of hope as well.