Im not sure if this is possible but I think (hint:think) i saw it somewhere once, which i think is way better than the 20 char limit ( no disrespect here and the 20 char doesnt bother me).
How it goes:
1-Each member will have the ability to vote if the post is good/bad/average etc..
2- there is no number two fools.
3- Each member will then evaluate his post and be able why it was ranked like that,that way he will teach himself/herself over time how to reply better than the previous time.
its like the rank system on youtube where each video can be ranked or most article website, im pretty sure there has to be something like that for vb, i never operated a vb before but i saw it somewhere.
Why do I think this plan is better?
20 char limit isnt that much effective if you ask me, a post consisted of only 20 can be worthless or even a post of 20 paragraphs but with the rank system, it will show the original poster and the posters of the replies what others think about their posts and therefore they will improve it later.