I'd propose participation for X days and a very loose karma metric (e.g. non-negative karma to block out consistent hecklers) as a compromise. You don't want someone who posted once and disappears for months to be given elevated permissions, because the idea of the karma gate is to adjust to how the community works before getting more features.

semi-artbituarily, I'd say 2-3 months worth of distinct days making a comment or post should be enough time.

Yeah, the karma requirements mean you frequently see people adding noise to discussions rather than signal, just to get out there and seen. I rarely comment and haven't hit the 501 threshold to downvote despite being here for a number of years, mostly because I just upvote what I agree with rather than posting a "me too".

(And I'm now concerned that this comment will feel like a "me too" :) )